Name: isolation and respiratory measurements of mitochondria from arabidopsis thaliana
Uploaded: 2018-01-05T13:00:00
Description: Watch this Scientific Journal Video about Isolation and Respiratory Measurements of Mitochondria from Arabidopsis thaliana at JoVE.com

This study was supported by an Australian Research Council Centre of Excellence in Plant Energy Biology CE140100008, an Australian Research Council Future Fellowship (FT130100112) to MWM, and a Feodor Lynen Research Fellowship (Alexander von Humboldt Foundation, Germany) to JS.

This protocol is used for the isolation of intact mitochondria from Arabidopsis thaliana organs grown on soil using continuous colloidal density gradients. All procedures following the collection of the material are carried out at 4 &#176;C.
1. Preparation of Grinding Medium, Wash Buffer, and Gradient Solutions
<ol>
	<li>Prepare 300 mL of grinding medium (minus ascorbate and cysteine) and 200 mL of 2x wash buffer per Table 1 one day prior to the isolation, keep them...

<ol>
	<li>Day, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highlights+in+plant+mitochondrial+research.+Methods+in+molecular+biology.">Highlights in plant mitochondrial research. Methods in molecular biology.</a> Plant mitochondria. 1305, v-xvi (2015).</li><li>Millar, A. H., Carrie, C., Pogson, B., Whelan, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploring+the+function-location+nexus:+Using+multiple+lines+of+evidence+in+defining+the+subcellular+location+of+plant+proteins.">Exploring the function-location nexus: Using multiple lines of evidence in defining the subcellular location of plant proteins.</a> Plant Cell. 21 (6), 1625-1631 (2009).</li><li>Eubel, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Free-flow+electrophoresis+for+purification+of+plant+mitochondria+by+surface+charge.">Free-flow electrophoresis for purification of plant mitochondria by surface charge.</a> Plant J. 52 (3), 583-594 (2007).</li><li>Murcha, M. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+import+into+plant+mitochondria:+Signals,+machinery,+processing,+and+regulation.">Protein import into plant mitochondria: Signals, machinery, processing, and regulation.</a> J. Exp. Bot. 65 (22), 6301-6335 (2014).</li><li>Carrie, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Approaches+to+defining+dual-targeted+proteins+in+Arabidopsis.">Approaches to defining dual-targeted proteins in Arabidopsis.</a> Plant J. 57 (6), 1128-1139 (2009).</li><li>Pinto, G., Radulovic, M., Godovac-Zimmermann, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatial+perspectives+in+the+redox+code+-+Mass+spectrometric+proteomics+studies+of+moonlighting+proteins.">Spatial perspectives in the redox code - Mass spectrometric proteomics studies of moonlighting proteins.</a> Mass Spectrom. Rev. , (2016).</li><li>Day, D. A., Neuburger, M., Douce, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biochemical+characterisation+of+chlorophyll-free+mitochondria+from+pea+leaves.">Biochemical characterisation of chlorophyll-free mitochondria from pea leaves.</a> Aust. J. Plant Physiol. 12 (3), 219-228 (1985).</li><li>Boersema, P. J., Raijmakers, R., Lemeer, S., Mohammed, S., Heck, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiplex+peptide+stable+isotope+dimethyl+labeling+for+quantitative+proteomics.">Multiplex peptide stable isotope dimethyl labeling for quantitative proteomics.</a> Nat. Protoc. 4 (4), 484-494 (2009).</li><li>Cheah, M. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Online+oxygen+kinetic+isotope+effects+using+membrane+inlet+mass+spectrometry+can+differentiate+between+oxidases+for+mechanistic+studies+and+calculation+of+their+contributions+to+oxygen+consumption+in+whole+tissues.">Online oxygen kinetic isotope effects using membrane inlet mass spectrometry can differentiate between oxidases for mechanistic studies and calculation of their contributions to oxygen consumption in whole tissues.</a> Anal Chem. 86 (10), 5171-5178 (2014).</li><li>Chrobok, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissecting+the+metabolic+role+of+mitochondria+during+developmental+leaf+senescence.">Dissecting the metabolic role of mitochondria during developmental leaf senescence.</a> Plant Physiol. 172 (4), 2132-2153 (2016).</li><li>Lee, C. P., Eubel, H., O'Toole, N., Millar, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combining+proteomics+of+root+and+shoot+mitochondria+and+transcript+analysis+to+define+constitutive+and+variable+components+in+plant+mitochondria.">Combining proteomics of root and shoot mitochondria and transcript analysis to define constitutive and variable components in plant mitochondria.</a> Phytochemistry. 72 (10), 1092-1098 (2011).</li><li>Lee, C. P., Eubel, H., Solheim, C., Millar, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitochondrial+proteome+heterogeneity+between+tissues+from+the+vegetative+and+reproductive+stages+of+Arabidopsis+thaliana+development.">Mitochondrial proteome heterogeneity between tissues from the vegetative and reproductive stages of Arabidopsis thaliana development.</a> J. Proteome Res. 11 (6), 3326-3343 (2012).</li><li>Millar, A. H., Whelan, J., Soole, K. L., Day, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organization+and+regulation+of+mitochondrial+respiration+in+plants.">Organization and regulation of mitochondrial respiration in plants.</a> Annu. Rev. Plant Biol. 62, 79-104 (2011).</li><li>Peters, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complex+I+-+complex+II+ratio+strongly+differs+in+various+organs+of+Arabidopsis+thaliana.">Complex I - complex II ratio strongly differs in various organs of Arabidopsis thaliana.</a> Plant Mol. Biol. 79 (3), 273-284 (2012).</li><li>Werhahn, W. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+and+characterization+of+the+preprotein+translocase+of+the+outer+mitochondrial+membrane+from+Arabidopsis+thaliana:+Identification+of+multiple+forms+of+TOM20.">Purification and characterization of the preprotein translocase of the outer mitochondrial membrane from Arabidopsis thaliana: Identification of multiple forms of TOM20.</a> Plant Physiol. 125 (2), 943-954 (2001).</li><li>Heazlewood, J. L., Howell, K. A., Whelan, J., Millar, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+an+analysis+of+the+rice+mitochondrial+proteome.">Towards an analysis of the rice mitochondrial proteome.</a> Plant Physiol. 132 (1), 230-242 (2003).</li></ol>

Typically, isolation of mitochondria from Arabidopsis leaves yields up 3 mg of mitochondria from approximately 80 - 100 3 - 4-week old plants, although yields of greater than 5 mg can often be achieved with thorough grinding. The yield varies with growth conditions and decreases dramatically as leaves senesce, although mitochondria structure seems to be well maintained during senescence9. One of the most critical features to obtain a good yield is the method of grinding to lyse cells to release mi...

The history of plant mitochondrial research goes back over 100 years1. Intact mitochondria were first isolated in the early 1950s using differential centrifugation. The advent of a colloidal density gradient in the 1980s allowed mitochondria to be purified without suffering osmotic adjustment. While gradient purified mitochondria are suitable for most purposes, due to the sensitivity of mass spectrometry, even relatively minor contaminants can be detected and may be inappropriately assigned a mitochondrial location2. The use of free flow electrophoresis can remove both plastidic and peroxisome contamination3, but free flow electrophoresis is a highly specialized technique and is not required for the vast majority of studies. Furthermore, when determining the location of a protein it needs to be remembered that dual or multiple targeting of proteins occurs in cells. Over 100 dual targeted proteins are described for chloroplasts/plastids and mitochondria4, and a number of proteins targeted to mitochondria and peroxisomes are also known5. Furthermore, the re-location of proteins under specific stimuli, e.g. oxidative stress, is an emerging theme in cell biology6. Thus, the location of proteins needs to be considered in the context of the biology studied, and a variety of approaches are used to determine and verify location2.
Mitochondria are typically isolated from plant tissues by homogenization, a balance is required between breaking open the cell wall to release mitochondria, and not damaging the mitochondria. Traditionally, with potato and cauliflower, homogenization involves using household blender/juicer apparatus to make a liquid extract in a buffer with various components to maintain activity.&#160;Isolation of mitochondria from pea leaves, (a popular material for mitochondrial isolation using young seedlings (~10 days old), utilizes a blender to lyse cells as the leaf material is soft. With the availability of Arabidopsis thaliana T-DNA insertional knock-out lines, the need to be able to purify mitochondria to carry out functional studies has necessitated the development of methods to isolate mitochondria from leaf, root or flower tissue. Overall the methods developed for other plants worked well7, with the perquisite that grinding of the material needed to be optimized. For Arabidopsis this can be achieved in a variety of ways (see below), and differs between tissue types (root versus shoot). The use of the continuous gradient can also be optimized as the density of mitochondria from different organs or developmental stages means they can migrate differently. Thus, for maximum separation the density of the gradient can be refined to ensure to achieve best separation.
Once purified the mitochondria can be used for a variety of studies, including protein and tRNA uptake experiments, enzyme activity assays, respiratory chain measurements and western blot analyses. Isolated mitochondria can also be used for mass spectrometry analyses of protein abundance. Targeted multiple reaction monitoring (MRM) analyses allows for the quantification of defined proteins, but require significant assay development. In contrast, quantification by dimethyl or other isotope labels8, provides a discovery approach in identifying differences across the whole proteome that can be used to uncover novel biological insights.

<table>
	<tbody>
		<tr>
			<td>ADP</td>
			<td>Sigma-Aldrich</td>
			<td>A2754</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Antimycin A</td>
			<td>Sigma-Aldrich</td>
			<td>A8674</td>
			<td>Chemical, dissolve in ethanol</td>
		</tr>
		<tr>
			<td>AOX antibody</td>
			<td>from Tom Elthon</td>
			<td></td>
			<td>Elthon et al., 1989</td>
		</tr>
		<tr>
			<td>Ascorbate</td>
			<td>Sigma-Aldrich</td>
			<td>A0157</td>
			<td>Ascorbate Oxidase from Cucurbita sp.</td>
		</tr>
		<tr>
			<td>ATP</td>
			<td>Sigma-Aldrich</td>
			<td>A26209</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Bovine serum albumin (BSA)</td>
			<td>Bovogen</td>
			<td>BSAS 1.0</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Clarity western ECL substrate</td>
			<td>Bio-Rad Laboratories</td>
			<td>1705061</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Criterion Stain-Free Precast Gels 8-16% 18 Wells</td>
			<td>Bio-Rad Laboratories</td>
			<td>5678104</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Cyanide</td>
			<td>Sigma-Aldrich</td>
			<td>60178</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Cytochrome c</td>
			<td>Sigma-Aldrich</td>
			<td>C3131</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Difco Agar, granulated</td>
			<td>BD Biosciences</td>
			<td>214530</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Dithiotreitol</td>
			<td>Sigma-Aldrich</td>
			<td>D0632</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>EDTA disodium salt</td>
			<td>Sigma-Aldrich</td>
			<td>E5134</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Gamborg B-5 Basal Medium</td>
			<td>Austratec</td>
			<td>G398-100L</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Gamborg Vitamin Solution (1000x)</td>
			<td>Austratec</td>
			<td>G219-100ML</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Goat Anti-Mouse IgG (H + L)-HRP Conjugate</td>
			<td>Bio-Rad Laboratories</td>
			<td>1706516-2ml</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Goat Anti-Rabbit IgG (H + L)-HRP Conjugate</td>
			<td>Bio-Rad Laboratories</td>
			<td>1706515-2ml</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>L-Cysteine</td>
			<td>Sigma</td>
			<td>C7352-100G</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Magnesium sulfate</td>
			<td>Sigma-Aldrich</td>
			<td>230391</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Murashige &#38; Skoog Basal Salt Mixture (MS)</td>
			<td>Austratec</td>
			<td>M524-100L</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Myxothiazol</td>
			<td>Sigma-Aldrich</td>
			<td>T5580</td>
			<td>Chemical, dissolve in ethanol</td>
		</tr>
		<tr>
			<td>NADH</td>
			<td>Sigma-Aldrich</td>
			<td>N8129</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Ndufs4 antibody</td>
			<td>from Etienne Meyer</td>
			<td></td>
			<td>Meyer et al., 2009</td>
		</tr>
		<tr>
			<td>n-Propyl gallate</td>
			<td>Sigma-Aldrich</td>
			<td>P3130</td>
			<td>Chemical, dissolve in ethanol</td>
		</tr>
		<tr>
			<td>Percoll</td>
			<td>GE Healthcare</td>
			<td>17-0891-01</td>
			<td>Chemical, colloidal density gradient</td>
		</tr>
		<tr>
			<td>Polyvinylpyrrolidone (PVP40)</td>
			<td>Sigma-Aldrich</td>
			<td>PVP40</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Potassium cyanide</td>
			<td>Sigma-Aldrich</td>
			<td>60178</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Potassium phosphate monobasic (KH2PO4)</td>
			<td>Sigma-Aldrich</td>
			<td>P5655</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Pyruvate</td>
			<td>Sigma-Aldrich</td>
			<td>P2256</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>Chem-Supply</td>
			<td>SA046</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Sodium dithionite</td>
			<td>Sigma-Aldrich</td>
			<td>157953</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Sodium L-ascorbate</td>
			<td>Sigma</td>
			<td>A4034-100G</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Succinate</td>
			<td>Sigma-Aldrich</td>
			<td>S2378</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Chem-Supply</td>
			<td>SA030</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>TES</td>
			<td>Sigma-Aldrich</td>
			<td>T1375</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Tetrasodium pyrophosphate (Na4P2O7 &#183; 10H2O)</td>
			<td>Sigma-Aldrich</td>
			<td>221368</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Trans-Blot Turbo RTA Midi Nitrocellulose Transfer Kit</td>
			<td>Bio-Rad Laboratories</td>
			<td>1704271</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Triton-X 100</td>
			<td>Sigma-Aldrich</td>
			<td>X100</td>
			<td>Chemical, detergent</td>
		</tr>
		<tr>
			<td>Western Blocking Reagent</td>
			<td>Sigma</td>
			<td>11921681001</td>
			<td>Chemical</td>
		</tr>
		<tr>
			<td>Balance</td>
			<td>Mettler Toledo</td>
			<td>XS204</td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Beakers</td>
			<td>Isolab</td>
			<td>50 mL</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Beckman Coulter</td>
			<td>Avanti J-26XP</td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Centrifuge tubes</td>
			<td>Nalgene</td>
			<td>3117-9500</td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Circulator</td>
			<td>Julabo</td>
			<td>1124971</td>
			<td>Attached to oxygen electrode chamber</td>
		</tr>
		<tr>
			<td>Conical flask</td>
			<td>Isolab</td>
			<td>500 mL</td>
			<td></td>
		</tr>
		<tr>
			<td>Dropper</td>
			<td></td>
			<td>3 mL</td>
			<td></td>
		</tr>
		<tr>
			<td>Fixed angle rotor</td>
			<td>Beckman Coulter</td>
			<td>JA25.5</td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Funnel</td>
			<td>Per Alimenti</td>
			<td>14 cm</td>
			<td>For filtering</td>
		</tr>
		<tr>
			<td>Gradient pourer</td>
			<td>Bio-Rad</td>
			<td>165-4120</td>
			<td>For preparation of gradients</td>
		</tr>
		<tr>
			<td>Magnetic Stirrer ATE</td>
			<td>VELP Scientifica</td>
			<td>F20300165</td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Miracloth</td>
			<td>VWR</td>
			<td>EM475855-1R</td>
			<td>Filtration material</td>
		</tr>
		<tr>
			<td>Mortar and pestle</td>
			<td>Jamie Oliver</td>
			<td>Granite, 6 Inch</td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>O2view</td>
			<td>Hansatech Instruments</td>
			<td></td>
			<td>Oxygen monitoring software</td>
		</tr>
		<tr>
			<td>Oxygraph Plus System</td>
			<td>Hansatech Instruments</td>
			<td>1187253</td>
			<td>Clark-type oxygen electrode</td>
		</tr>
		<tr>
			<td>Paintbrush</td>
			<td>Artist first choice</td>
			<td>1008R-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Parafilm</td>
			<td>Bemis</td>
			<td>PM-996</td>
			<td>plastic paraffin film</td>
		</tr>
		<tr>
			<td>Peristaltic pump</td>
			<td>Gilson</td>
			<td>F155001</td>
			<td>For preparation of gradients</td>
		</tr>
		<tr>
			<td>PVC peristaltic tubing</td>
			<td>Gilson</td>
			<td>F117930</td>
			<td>For preparation of gradients</td>
		</tr>
		<tr>
			<td>Water bath</td>
			<td>VELP Scientifica</td>
			<td>OCB</td>
			<td>Equipment</td>
		</tr>
	</tbody>
</table>

isolation and respiratory measurements of mitochondria from arabidopsis thaliana

Mitochondria are essential organelles involved in numerous metabolic pathways in plants, most notably the production of adenosine triphosphate (ATP) from the oxidation of reduced compounds such as nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH2). The complete annotation of the Arabidopsis thaliana genome has established it as the most widely used plant model system, and thus the need to purify mitochondria from a variety of organs (leaf, root, or flower) is necessary to fully utilize the tools that are now available for Arabidopsis to study mitochondrial biology. Mitochondria are isolated by homogenization of the tissue using a variety of approaches, followed by a series of differential centrifugation steps producing a crude mitochondrial pellet that is further purified using continuous colloidal density gradient centrifugation. The colloidal density material is subsequently removed by multiple centrifugation steps. Starting from 100 g of fresh leaf tissue, 2 - 3 mg of mitochondria can be routinely obtained. Respiratory experiments on these mitochondria display typical rates of 100 - 250 nmol O2 min-1 mg total mitochondrial protein-1 (NADH-dependent rate) with the ability to use various substrates and inhibitors to determine which substrates are being oxidized and the capacity of the alternative and cytochrome terminal oxidases. This protocol describes an isolation method of mitochondria from Arabidopsis thaliana leaves using continuous colloidal density gradients and an efficient respiratory measurements of purified plant mitochondria.

Using this protocol, we were able to detect different mitochondrial proteins by SDS-PAGE and immunoblotting. As shown in Figure 3A, the protein isolated from water culture tissue is sufficient to detect a faint band (2 &#181;g). Signal intensity increases proportionately to the amounts loaded. For mitochondria isolated from tissues grown on plates (Figure 3B), the response to high light stress treatment in different genotypes can...

Watch this Scientific Journal Video about Isolation and Respiratory Measurements of Mitochondria from Arabidopsis thaliana at JoVE.com

Isolation and Respiratory Measurements of Mitochondria from Arabidopsis thaliana

As mitochondria are only a small percentage of the plant cell, they need to be purified for a range of studies. Mitochondria can be isolated from a variety of plant organs by homogenization, followed by differential and density gradient centrifugation to obtain a highly purified mitochondrial fraction.

Isolation and Respiratory Measurements of Mitochondria from Arabidopsis thaliana

Mitochondria are essential organelles involved in numerous metabolic pathways in plants, most notably the production of adenosine triphosphate (ATP) from ...

The overall goal of isolating intact and pure plant mitochondria is to study respiration, mitochondrial composition, biogenesis, and metabolism. This method can help answer key questions in plant energy biology, such as the importance of mitochondria and stress tolerance, under changing environmental conditions. The main advantage of this technique is that sufficient quantities of pure, intact, and functional mitochondria could be isolated from relatively small quantities of plant tissue.Demonstrating the procedure will be Wenhui Lyu, and Jennifer Selinski, From my laboratory. On the day of mitochondrial isolation, wash the gradient pourer and PVC peristaltic tubing with deionized water to prepare the gradients. Incline to position two 50 mL centrifuge tubes on ice, such that the peristaltic tubing outlet touches the wall of the tubes.Then turn the black lever down to close the connection between the inner and outer chambers. Place the gradient pourer with the magnetic stir bar inside the inner chamber on a magnetic stirrer. Then, pour 35 mL of heavy gradient solution into the inner chamber.Dispense half of the heavy gradient solution through the peristaltic pump, at 300 mL per hour, into two centrifuge tubes, kept on ice. Then pour 35 mL of light gradient solution into the outer chamber. Immediately, turn the black lever up halfway to resume connection between the inner and the outer chambers, for the solutions to mix gently.Expel the entire gradient mixture from the chambers, at a rate of 60 mL per hour, to form two continuous 0%to 4.4%PVP gradients. Always keep the gradients on ice before use. It is important not to overground the plant tissue, otherwise the mitochondria will break down.For a single preparation, cut the whole rosette tissue from at least 80 four week old Arabidopsis plants, grown on soil. Then add half of the cut plant tissues to a cooled large mortar and pestle, containing 75 mL of grinding medium. Then use grinding medium to moisten four layers of filtration material, with a pore size of 20 to 25 m.Use a plastic funnel to filter the homogeny through all four layers of filtration material, and collect it in a 500 mL conical flask. Use an additional 75 mL of grinding medium to grind the other half of the tissue. Then combine the entire homogenate in the filtration material, to filter out as much as possible.Use 150 mL of grinding medium to grind all of the remaining tissue on the filtration material, and filter into a 500 mL conical flask. Distribute the filtered homogenate in eight pre-chilled 50mL plastic centrifuge tubes. And centrifuge at 2, 500 g at four degrees celsius, in a fixed angle rotor, for five minutes.After pouring the supernatant into clean centrifuge tubes, centrifuge again at 17, 500 g, at four degrees celsius, for 20 minutes, in a fixed angle rotor. Leave 3 mL of supernatant in the tube. Then use a fine paintbrush to gently re-suspend the pellet in the remaining supernatant.Add 10 mL of single strength wash buffer to each of the tubes, and pool all four of the tubes into one centrifuge tube, resulting in two tubes total. Adjust the volume to 50mL with single strength wash buffer, and repeat the centrifugation steps. Using a very small quantity of wash buffer, disperse the pellet with the fine paintbrush, and then use a dropper to pool the crude mitochondrial pellet into a tube.Then carefully layer the mitochondrial suspension with a dropper, on two continuous 0%to 4%PVP gradients. Use single strength wash buffer to balance the weight of the tubes, and conduct a centrifugation run at 40, 000 g at four degrees celsius, for 40 minutes. Remember to turn off the brake.Cautiously aspirate the upper five centimeters of solution above the mitochondrial band. Then distribute the mitochondrial solution into two clean tubes, and fill with single strength wash buffer. Cover the mouth of the tube with plastic paraffin film, and invert it several times to evenly distribute the colloidal density gradient, and mitochondria.Then, centrifuge at 31, 000 g for 15 minutes at four degrees celsius, with slow brake. Aspirate the supernatant and adjust the tube volume up to 50mL with single strength wash buffer. Invert several times for proper mixing.Centrifuge the solution at 31, 000 g for 15 minutes at four degrees celsius with slow brake. Aspirate the supernatant, and subsequently collect the mitochondrial pellet in 500 l of single strength wash buffer, using a pipette with modified 200 l tip. With the plunger open, add 970 l of air saturated respiration medium to the reaction chamber.Then add 150 g of total mitochondrial protein, using a modified pipette, and 500 M Adenosine Triphosphate to the reaction chamber, to determine mitochondrial respiration. Use a magnetic stir bar to continuously stir the mitochondrial suspension. After closing the plunger, click Start Recording to record oxygen consumption.Wait for a minute or two, to check for a linear oxygen consumption trace, indicating stable oxygen consumption. Then, add 5 mM of succinate, and record the oxygen consumption for approximately two minutes. Add 1 mM Adenosine Diphosphate, and keep recording the oxygen consumption rate for another two minutes.Next, add 1 mM Nicotinamide Adenine Dinucleotide Hydrogen, and continue recording oxygen consumption for around four to eight minutes. Then add reagents to inhibit the cytochrome C pathway, and keep recording the oxygen consumption via alternative oxidase, for about two minutes. KCN, myxothiazol, and antimycin A are all respiratory poisons.It is important to follow the safety instructions in the MSDS data sheets. Please note that different countries will have different legislations for the use of these inhibitors in our experiments. Next, add 5 mM dithiothreitol, and 10 mM pyruvate to activate the alternative oxidase.And keep recording for another five to seven minutes. Finally, add 500 mM N-propyl gallate, and record for two minutes. A representative gradient, showing the presence of greenish-white mitochondrial fraction near the bottom of the gradient solution.Thylakoids and other contaminants present on top of the gradient solution, are indicated in dark green bands. Representative traces of oxygen consumption by mitochondria, to show the outer membrane integrity before oxygen consumption measurement. The outer membrane integrity was well preserved and about 90%intact.Representative traces of oxygen consumption by mitochondria, after adding substrates, inhibitors, and effectors. The results show a compromised cytochrome c, and alternative oxidase pathway. After watching this video, you should have a good understanding of how to isolate and analyze plant mitochondria.

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Unit 1

Mitochondria and Energy Production

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Analyses of Mitochondrial Calcium Influx in Isolated Mitochondria and Cultured Cells

Ca2+ handling by mitochondria is a critical function regulating both physiological and pathophysiological processes in a broad spectrum of cells. The ability to accurately measure the influx and efflux of Ca2+ from mitochondria is important for determining the role of mitochondrial Ca2+ handling in these processes. In this report, we present two methods for the measurement of mitochondrial Ca2+ handling in both isolated mitochondria and cultured cells. We first detail a plate reader-based platform for measuring mitochondrial Ca2+ uptake using the Ca2+ sensitive dye calcium green-5N. The plate reader-based format circumvents the need for specialized equipment, and the calcium green-5N dye is ideally suited for measuring Ca2+ from isolated tissue mitochondria. For our application, we describe the measurement of mitochondrial Ca2+ uptake in mitochondria isolated from mouse heart tissue; however, this procedure can be applied to measure mitochondrial Ca2+ uptake in mitochondria isolated from other tissues such as liver, skeletal muscle, and brain. Secondly, we describe a confocal microscopy-based assay for measurement of mitochondrial Ca2+ in permeabilized cells using the Ca2+ sensitive dye Rhod-2/AM and imaging using 2-dimensional laser-scanning microscopy. This permeabilization protocol eliminates cytosolic dye contamination, allowing for specific recording of changes in mitochondrial Ca2+. Moreover, laser-scanning microscopy allows for high frame rates to capture rapid changes in mitochondrial Ca2+ in response to various drugs or reagents applied in the external solution. This protocol can be applied to measure mitochondrial Ca2+ uptake in many cell types including primary cells such as cardiac myocytes and neurons, and immortalized cell lines.

Here, we present two protocols for the measurement of mitochondrial Ca2+ influx in isolated mitochondria and cultured cells. For isolated mitochondria, we detail a plate reader-based Ca2+ import assay using the Ca2+ sensitive dye calcium green-5N. For cultured cells, we describe a confocal microscopy method using the Ca2+ dye Rhod-2/AM.

Ca2+ handling by mitochondria is a critical function regulating both physiological and pathophysiological processes in a broad spectrum of cells. The ...

Rapid Isolation of the Mitoribosome from HEK Cells

The human mitochondria possess a dedicated set of ribosomes (mitoribosomes) that translate 13 essential protein components of the oxidative phosphorylation complexes encoded by the mitochondrial genome. Since all proteins synthesized by human mitoribosomes are integral membrane proteins, human mitoribosomes are tethered to the mitochondrial inner membrane during translation. Compared to the cytosolic ribosome the mitoribosome has a sedimentation coefficient of 55S, half the rRNA content, no 5S rRNA and 36 additional proteins. Therefore, a higher protein-to-RNA ratio and an atypical structure make the human mitoribosome substantially distinct from its cytosolic counterpart.
Despite the central importance of the mitoribosome to life, no protocols were available to purify the intact complex from human cell lines. Traditionally, mitoribosomes were isolated from mitochondria-rich animal tissues that required kilograms of starting material. We reasoned that mitochondria in dividing HEK293-derived human cells grown in nutrient-rich expression medium would have an active mitochondrial translation, and, therefore, could be a suitable source of material for the structural and biochemical studies of the mitoribosome. To investigate its structure, we developed a protocol for large-scale purification of intact mitoribosomes from HEK cells. Herein, we introduce nitrogen cavitation method as a faster, less labor-intensive and more efficient alternative to traditional mechanical shear-based methods for cell lysis. This resulted in preparations of the mitoribosome that allowed for its structural determination to high resolution, revealing the composition of the intact human mitoribosome and its assembly intermediates. Here, we follow up on this work and present an optimized and more cost-effective method requiring only ~1010 cultured HEK cells. The method can be employed to purify human mitoribosomal translating complexes, mutants, quality control assemblies and mitoribosomal subunits intermediates. The purification can be linearly scaled up tenfold if needed, and also applied to other types of cells.

Mitochondria have specialized ribosomes that diverged from their bacterial and cytoplasmic counterparts. Here we show how mitoribosomes can be obtained from their native compartment in HEK cells. The method involves isolation of mitochondria from suspension cells and consequent purification of mitoribosomes.

The human mitochondria possess a dedicated set of ribosomes (mitoribosomes) that translate 13 essential protein components of the oxidative ...

Preparation of Chloroplast Sub-compartments from Arabidopsis for the Analysis of Protein Localization by Immunoblotting or Proteomics

Chloroplasts are major components of plant cells. Such plastids fulfill many crucial functions, such as assimilation of carbon, sulfur and nitrogen as well as synthesis of essential metabolites. These organelles consist of the following three key sub-compartments. The envelope, characterized by two membranes, surrounds the organelle and controls the communication of the plastid with other cell compartments. The stroma is the soluble phase of the chloroplast and the main site where carbon dioxide is converted into carbohydrates. The thylakoid membrane is the internal membrane network consisting of grana (flat compressed sacs) and lamellae (less dense structures), where oxygenic photosynthesis takes place. The present protocol describes step by step procedures required for the purification, using differential centrifugations and Percoll gradients, of intact chloroplasts from Arabidopsis, and their fractionation, using sucrose gradients, in three sub-compartments (i.e., envelope, stroma, and thylakoids). This protocol also provides instructions on how to assess the purity of these fractions using markers associated to the various chloroplast sub-compartments. The method described here is valuable for subplastidial localization of proteins using immunoblotting, but also for subcellular and subplastidial proteomics and other studies.

Here, we describe a method to purify intact chloroplasts from Arabidopsis leaves and their three main sub-compartments (envelope, stroma, and thylakoids), using a combination of differential centrifugations, continuous Percoll gradients, and discontinuous sucrose gradients. The method is valuable for subplastidial and subcellular localization of proteins by immunoblotting and proteomics.

Chloroplasts are major components of plant cells. Such plastids fulfill many crucial functions, such as assimilation of carbon, sulfur and nitrogen as ...

Isolation of Tissue Extracellular Vesicles from the Liver

Extracellular vesicles (EVs) can be released from many different cell types and detected in most, if not all, body fluids. EVs can participate in cell-to-cell communication by shuttling bioactive molecules such as RNA or protein from one cell to another. Most studies of EVs have been performed in cell culture models or in EVs isolated from body fluids. There is emerging interest in the isolation of EVs from tissues to study their contribution to physiological processes and how they are altered in disease. The isolation of EVs with sufficient yield from tissues is technically challenging because of the need for tissue dissociation without cellular damage. This method describes a procedure for the isolation of EVs from mouse liver tissue. The method involves a two-step process starting with in situ collagenase digestion followed by differential ultra-centrifugation. Tissue perfusion using collagenase provides an advantage over mechanical cutting or homogenization of liver tissue due to its increased yield of obtained EVs. The use of this two-step process to isolate EVs from the liver will be useful for the study of tissue EVs.

This is a protocol to isolate tissue extracellular vesicles (EVs) from the liver. The protocol describes a two-step process involving collagenase perfusion followed by differential ultracentrifugation to isolate liver tissue EVs.

Extracellular vesicles (EVs) can be released from many different cell types and detected in most, if not all, body fluids. EVs can participate in ...

Hybrid Clear/Blue Native Electrophoresis for the Separation and Analysis of Mitochondrial Respiratory Chain Supercomplexes

Complexes of the oxidative phosphorylation machinery form supramolecular protein arrangements named supercomplexes (SCs), which are believed to confer structural and functional advantages to mitochondria. SCs have been identified in many species, from yeast to mammal, and an increasing number of studies report disruption of their organization in genetic and acquired human diseases. As a result, an increasing number of laboratories are interested in analyzing SCs, which can be methodologically challenging. This article presents an optimized protocol that combines the advantages of Blue- and Clear-Native PAGE methods to resolve and analyze SCs in a time-effective manner. With this hybrid CN/BN-PAGE method, mitochondrial SCs extracted with optimal amounts of the mild detergent digitonin are exposed briefly to the anionic dye Coomassie Blue (CB) at the beginning of the electrophoresis, without exposure to other detergents. This short exposure to CB allows to separate and resolve SCs as effectively as with traditional BN-PAGE methods, while avoiding the negative impact of high CB levels on in-gel activity assays, and labile protein-protein interactions within SCs. With this protocol it is thus possible to combine precise and rapid in gel activity measurements with analytical techniques involving 2D electrophoresis, immuno-detection, and/or proteomics for advanced analysis of SCs.

Here we present a protocol to extract, resolve and identify mitochondrial supercomplexes which minimizes exposure to detergents and Coomassie Blue. This protocol offers an optimal balance between resolution, and preservation of enzyme activities, while minimizing the risk of losing labile protein-protein interactions.

Complexes of the oxidative phosphorylation machinery form supramolecular protein arrangements named supercomplexes (SCs), which are believed to confer ...

Mitochondria and Endoplasmic Reticulum Imaging by Correlative Light and Volume Electron Microscopy

Cellular organelles, such as mitochondria and endoplasmic reticulum (ER), create a network to perform a variety of functions. These highly curved structures are folded into various shapes to form a dynamic network depending on the cellular conditions. Visualization of this network between mitochondria and ER has been attempted using super-resolution fluorescence imaging and light microscopy; however, the limited resolution is insufficient to observe the membranes between the mitochondria and ER in detail. Transmission electron microscopy provides good membrane contrast and nanometer-scale resolution for the observation of cellular organelles; however, it is exceptionally time-consuming when assessing the three-dimensional (3D) structure of highly curved organelles. Therefore, we observed the morphology of mitochondria and ER via correlative light-electron microscopy (CLEM) and volume electron microscopy techniques using enhanced ascorbate peroxidase 2 and horseradish peroxidase staining. An en bloc staining method, ultrathin serial sectioning (array tomography), and volume electron microscopy were applied to observe the 3D structure. In this protocol, we suggest a combination of CLEM and 3D electron microscopy to perform detailed structural studies of mitochondria and ER.

We present a protocol to study the distribution of mitochondria and endoplasmic reticulum in whole cells after genetic modification using correlative light and volume electron microscopy including ascorbate peroxidase 2 and horseradish peroxidase staining, serial sectioning of cells with and without the target gene in the same section, and serial imaging via electron microscopy.

Cellular organelles, such as mitochondria and endoplasmic reticulum (ER), create a network to perform a variety of functions. These highly curved ...

Real-Time, Semi-Automated Fluorescent Measurement of the Airway Surface Liquid pH of Primary Human Airway Epithelial Cells

In recent years, the importance of mucosal surface pH in the airways has been highlighted by its ability to regulate airway surface liquid (ASL) hydration, mucus viscosity and activity of antimicrobial peptides, key parameters involved in innate defense of the lungs. This is of primary relevance in the field of chronic respiratory diseases such as cystic fibrosis (CF) where these parameters are dysregulated. While different groups have studied ASL pH both in vivo and in vitro, their methods report a relatively wide range of ASL pH values and even contradictory findings regarding any pH differences between non-CF and CF cells. Furthermore, their protocols do not always provide enough details in order to ensure reproducibility, most are low throughput and require expensive equipment or specialized knowledge to implement, making them difficult to establish in most labs. Here we describe a semi-automated fluorescent plate reader assay that enables the real-time measurement of ASL pH under thin film conditions that more closely resemble the in vivo situation. This technique allows for stable measurements for many hours from multiple airway cultures simultaneously and, importantly, dynamic changes in ASL pH in response to agonists and inhibitors can be monitored. To achieve this, the ASL of fully differentiated primary human airway epithelial cells (hAECs) are stained overnight with a pH-sensitive dye in order to allow for the reabsorption of the excess fluid to ensure thin film conditions. After fluorescence is monitored in the presence or absence of agonists, pH calibration is performed in situ to correct for volume and dye concentration. The method described provides the required controls to make stable and reproducible ASL pH measurements, which ultimately could be used as a drug discovery platform for personalized medicine, as well as adapted to other epithelial tissues and experimental conditions, such as inflammatory and/or host-pathogen models.

We present a protocol to make dynamic measurements of the airway surface liquid pH under thin film conditions using a plate-reader.

In recent years, the importance of mucosal surface pH in the airways has been highlighted by its ability to regulate airway surface liquid (ASL) ...

Interactions with and Membrane Permeabilization of Brain Mitochondria by Amyloid Fibrils

A growing body of evidence indicates that membrane permeabilization, including internal membranes such as mitochondria, is a common feature and primary mechanism of amyloid aggregate-induced toxicity in neurodegenerative diseases. However, most reports describing the mechanisms of membrane disruption are based on phospholipid model systems, and studies directly targeting events occurring at the level of biological membranes are rare. Described here is a model for studying the mechanisms of amyloid toxicity at the membrane level. For mitochondrial isolation, density gradient medium is used to obtain preparations with minimal myelin contamination. After mitochondrial membrane integrity confirmation, the interaction of amyloid fibrils arising from &#945;-synuclein, bovine insulin, and hen egg white lysozyme (HEWL) with rat brain mitochondria, as an in vitro biological model, is investigated. The results demonstrate that treatment of brain mitochondria with fibrillar assemblies can cause different degrees of membrane permeabilization and ROS content enhancement. This indicates structure-dependent interactions between amyloid fibrils and mitochondrial membrane. It is suggested that biophysical properties of amyloid fibrils and their specific binding to mitochondrial membranes may provide explanations for some of these observations.

Provided here is a protocol for investigating the interactions between native form, prefibrillar, and mature amyloid fibrils of different peptides and proteins with mitochondria isolated from different tissues and various areas of the brain.

A growing body of evidence indicates that membrane permeabilization, including internal membranes such as mitochondria, is a common feature and primary ...

Generation and Assembly of Virus-Specific Nucleocapsids of the Respiratory Syncytial Virus

The use of an authentic RNA template is critical to advance the fundamental knowledge of viral RNA synthesis that can guide both mechanistic discovery and assay development in virology. The RNA template of nonsegmented negative-sense (NNS) RNA viruses, such as the respiratory syncytial virus (RSV), is not an RNA molecule alone but rather a nucleoprotein (N) encapsidated ribonucleoprotein complex. Despite the importance of the authentic RNA template, the generation and assembly of such a ribonucleoprotein complex remain sophisticated and require in-depth elucidation. The main challenge is that the overexpressed RSV N binds non-specifically to cellular RNAs to form random nucleocapsid-like particles (NCLPs). Here, we established a protocol to obtain RNA-free N (N0) first by co-expressing N with a chaperone phosphoprotein (P), then assembling N0 with RNA oligos with the RSV-specific RNA sequence to obtain virus-specific nucleocapsids (NCs). This protocol shows how to overcome the difficulty in the preparation of this traditionally challenging viral ribonucleoprotein complex.

For in-depth mechanistic analysis of the respiratory syncytial virus (RSV) RNA synthesis, we report a protocol of utilizing the chaperone phosphoprotein (P) for coexpression of the RNA-free nucleoprotein (N0) for subsequent in vitro assembly of the virus-specific nucleocapsids (NCs).

The use of an authentic RNA template is critical to advance the fundamental knowledge of viral RNA synthesis that can guide both mechanistic discovery and ...

Measurement of Protein Import Capacity of Skeletal Muscle Mitochondria

Mitochondria are key metabolic and regulatory organelles that determine the energy supply as well as the overall health of the cell. In skeletal muscle, mitochondria exist in a series of complex morphologies, ranging from small oval organelles to a broad, reticulum-like network. Understanding how the mitochondrial reticulum expands and develops in response to diverse stimuli such as alterations in energy demand has long been a topic of research. A key aspect of this growth, or biogenesis, is the import of precursor proteins, originally encoded by the nuclear genome, synthesized in the cytosol, and translocated into various mitochondrial sub-compartments. Mitochondria have developed a sophisticated mechanism for this import process, involving many selective inner and outer membrane channels, known as the protein import machinery (PIM). Import into the mitochondrion is dependent on viable membrane potential and the availability of organelle-derived ATP through oxidative phosphorylation. Therefore its measurement can serve as a measure of organelle health. The PIM also exhibits a high level of adaptive plasticity in skeletal muscle that is tightly coupled to the energy status of the cell. For example, exercise training has been shown to increase import capacity, while muscle disuse reduces it, coincident with changes in markers of mitochondrial content. Although protein import is a critical step in the biogenesis and expansion of mitochondria, the process is not widely studied in skeletal muscle. Thus, this paper outlines how to use isolated and fully functional mitochondria from skeletal muscle to measure protein import capacity in order to promote a greater understanding of the methods involved and an appreciation of the importance of the pathway for organelle turnover in exercise, health, and disease.

Mitochondria are key metabolic organelles that exhibit a high level of phenotypic plasticity in skeletal muscle. The import of proteins from the cytosol is a critical pathway for organelle biogenesis, essential for the expansion of the reticulum and the maintenance of mitochondrial function. Therefore, protein import serves as a barometer of cellular health.

Mitochondria are key metabolic and regulatory organelles that determine the energy supply as well as the overall health of the cell. In skeletal muscle, ...