This work was financed by Fundo Europeu de Desenvolvimento Regional (FEDER) funds through the COMPETE 2020 - Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020, and by Portuguese funds through FCT - Funda&#231;&#227;o para a Ci&#234;ncia e a Tecnologia/Minist&#233;rio da Ci&#234;ncia, Tecnologia e Ensino Superior in the framework of the project POCI-01-0145-FEDER-028779 and the grant SFRH/BD/99715/2014 (CF).

1. Cyanobacterial released carbohydrate polymer isolation
<ol>
	<li>Polymer isolation and removal of contaminants 
	<ol>
		<li>Cultivate the cyanobacterial strain under standard conditions [e.g., 30 &#176;C under a 12 h light (50 &#956;E m&#8722;2s&#8722;1)/12 h dark regimen, with orbital shaking at 150 rpm]. Measure growth using standard protocols [e.g., optical density at 730 nm (OD730nm), chlorophyll a, dry-weight, etc.], then measure the production of released polysaccharides according to the phenol-sulfuric acid method16.</li>
		<li>Transfer the culture into dialysis membranes (12-14 kDa of molecular weight cut-off) and dialyze against a minimum of 10 volumes of deionized water for 24 h with continuous stirring. 
		NOTE: Depending on the volume of culture to dialyze and medium composition, it may be necessary to change the dialysis water.</li>
		<li>Centrifuge the culture at 15,000 x g for 15 min at 4 &#176;C. Transfer the supernatant to a new vial and discard the pellet (cells).</li>
		<li>Centrifuge again at 20,000 x g for 15 min at 4 &#176;C to remove contaminants such as cell wall debris or lipopolysaccharides (LPS).</li>
		<li>Transfer the supernatant to a glass beaker and discard the pellet.</li>
	</ol>
	</li>
	<li>Precipitation of the polymer
	<ol>
		<li>Add 2 volumes of 96% ethanol to the supernatant.</li>
		<li>Incubate the suspension at 4 &#176;C, at least overnight.</li>
		<li>Polymer recovery
		<ol>
			<li>For small or not visible amounts of precipitated polymer: centrifuge the suspension at 13,000 x g for 25 min at 4 &#176;C. Discard the supernatant and resuspend the pellet in 1 mL or 2 mL of autoclaved deionized water. Transfer the aqueous suspension to a vial. 
			CAUTION: The supernatant should be discarded gently, as it can become easily resuspended.</li>
			<li>For visible/large amounts of precipitated polymer: collect the precipitated polymer with sterile metal forceps to a vial. Squeeze the polymer and discard the excess ethanol.</li>
		</ol>
		</li>
		<li>Optional: depending on the degree of polymer purification required, repeat the precipitation step with 96% ethanol after resuspension of the polymers in deionized water.</li>
	</ol>
	</li>
	<li>Lyophilization of the polymer 
	<ol>
		<li>Keep the vials with the precipitated polymer at -80 &#176;C, at least overnight.</li>
		<li>Freeze-dry (lyophilize) the polymer for at least 48 h (do not let the suspension defrost before freeze-drying).</li>
		<li>Store the dried polymer at room temperature (RT) until further use. 
		NOTE: Storing the polymer in a desiccator is advisable, as it can absorb water over time.</li>
	</ol>
	</li>
</ol>
2. Cyanobacterial exoproteome isolation
<ol>
	<li>Medium concentration
	<ol>
		<li>Cultivate cyanobacteria under standard conditions [e.g., 30 &#176;C under a 12 h light (50 &#956;E m&#8722;2s&#8722;1)/12 h dark regimen, with orbital shaking at 150 rpm]. Monitor the cyanobacterium growth using standard procedures (e.g., OD730nm, chlorophyll a, dry-weight, etc.).</li>
		<li>Centrifuge the cultures at 4,000 x g, for 10 min at RT.</li>
		<li>Transfer the supernatant to a flask and discard the cell pellet.</li>
		<li>Filter the decanted medium through a 0.2 &#956;m pore size filter. 
		NOTE: The protocol can be paused here for a short time period, if the medium is kept at 4 &#176;C.</li>
		<li>Concentrate the medium approximately 500x (considering the initial volume of filtered medium), using centrifugal concentrators with a nominal molecular weight cut-off of 3 kDa. Centrifugation should be operated at 4,000 x g (maximum 1 h per centrifugation round) at 15 &#176;C. 
		CAUTION: For the majority of concentrator brands, the filter device needs to be rinsed by centrifugation with ultrapure water before use. Once the filter is wet, do not let it dry out. Leave enough fluid on the reservoir when the device is not being used. 
		NOTE: Reducing the centrifugation temperature to 4 &#176;C may be helpful if the aim is to study protein activity, though it will increase the time necessary for sample concentration. The protocol can be paused between centrifugation steps for short time periods if the medium is kept at 4 &#176;C.</li>
		<li>Rinse the walls of the filter device sample reservoir with the concentrated sample and transfer the content to a microcentrifuge tube.</li>
		<li>Perform an additional washing step of the filter device sample reservoir with autoclaved culture medium to ensure maximal exoproteome recovery. 
		NOTE: To quantify the percentage of recovery, follow the specific manufacturer&#8217;s instructions.</li>
		<li>Store the exoproteome samples at -20 &#176;C until further use. 
		NOTE: Addition of protease inhibitors is recommended for long-term storage.</li>
	</ol>
	</li>
	<li>Analysis of the exoproteome
	<ol>
		<li>Quantify the protein content by BCA protein assay in 96-well plate according to the manufacturer&#8217;s instructions.</li>
		<li>Separate the proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), using standard staining protocols (e.g., Coomassie blue, silver staining).</li>
		<li>Cut out the bands/gel regions of interest and collect them in different microcentrifuge tubes containing appropriate volumes of ultra-pure water.</li>
		<li>Proceed with identification and analysis of the proteins by mass spectrometry.</li>
	</ol>
	</li>
</ol>

<ol>
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H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancement+of+human+adaptive+immune+responses+by+administration+of+a+high-molecular-weight+polysaccharide+extract+from+the+cyanobacterium+Arthrospira+platensis.">Enhancement of human adaptive immune responses by administration of a high-molecular-weight polysaccharide extract from the cyanobacterium Arthrospira platensis.</a> Journal of Medicinal Food. 11 (2), 313-322 (2008).</li><li>Wang, H. B., Wu, S. J., Liu, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+polysaccharides+from+cyanobacteria+Nostoc+commune+and+their+antioxidant+activities.">Preparation of polysaccharides from cyanobacteria Nostoc commune and their antioxidant activities.</a> Carbohydrate Polymers. 99, 553-555 (2014).</li><li>Ozturk, S., Aslim, B., Suludere, Z., Tan, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metal+removal+of+cyanobacterial+exopolysaccharides+by+uronic+acid+content+and+monosaccharide+composition.">Metal removal of cyanobacterial exopolysaccharides by uronic acid content and monosaccharide composition.</a> Carbohydrate Polymers. 101, 265-271 (2014).</li><li>Han, P. P., 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=Emulsifying,+flocculating,+and+physicochemical+properties+of+exopolysaccharide+produced+by+cyanobacterium+Nostoc+flagelliforme.">Emulsifying, flocculating, and physicochemical properties of exopolysaccharide produced by cyanobacterium Nostoc flagelliforme.</a> Applied Biochemistry and Biotechnology. 172 (1), 36-49 (2014).</li><li>Leite, J. P., 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=Cyanobacterium&#8208;Derived+Extracellular+Carbohydrate+Polymer+for+the+Controlled+Delivery+of+Functional+Proteins.">Cyanobacterium&#8208;Derived Extracellular Carbohydrate Polymer for the Controlled Delivery of Functional Proteins.</a> Macromolecular Bioscience. 17 (2), 1600206 (2017).</li><li>Estevinho, B. N., 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=Application+of+a+cyanobacterial+extracellular+polymeric+substance+in+the+microencapsulation+of+vitamin+B12.">Application of a cyanobacterial extracellular polymeric substance in the microencapsulation of vitamin B12.</a> Powder Technology. 343, 644-651 (2019).</li><li>Klock, J. H., Wieland, A., Seifert, R., Michaelis, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+polymeric+substances+(EPS)+from+cyanobacterial+mats:+characterisation+and+isolation+method+optimisation.">Extracellular polymeric substances (EPS) from cyanobacterial mats: characterisation and isolation method optimisation.</a> Marine Biology. 152 (5), 1077-1085 (2007).</li><li>Delattre, C., Pierre, G., Laroche, C., Michaud, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production,+extraction+and+characterization+of+microalgal+and+cyanobacterial+exopolysaccharides.">Production, extraction and characterization of microalgal and cyanobacterial exopolysaccharides.</a> Biotechnology Advances. 34 (7), 1159-1179 (2016).</li><li>Costa, T. R., 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=Secretion+systems+in+gram-negative+bacteria:+structural+and+mechanistic+insights.">Secretion systems in gram-negative bacteria: structural and mechanistic insights.</a> Nature Reviews Microbiology. 13 (6), 343-359 (2015).</li><li>Roier, S., Zingl, F. G., Cakar, F., Schild, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bacterial+outer+membrane+vesicle+biogenesis:+a+new+mechanism+and+its+implications.">Bacterial outer membrane vesicle biogenesis: a new mechanism and its implications.</a> Microbial Cell. 3 (6), 257-259 (2016).</li><li>Sergeyenko, T. V., Los, 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=Identification+of+secreted+proteins+of+the+cyanobacterium+Synechocystis+sp.+strain+PCC+6803.">Identification of secreted proteins of the cyanobacterium Synechocystis sp. strain PCC 6803.</a> FEMS Microbiology Letters. 193 (2), 213-216 (2000).</li><li>Oliveira, P., 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=The+versatile+TolC-like+Slr1270+in+the+cyanobacterium+Synechocystis+sp.+PCC+6803.">The versatile TolC-like Slr1270 in the cyanobacterium Synechocystis sp. PCC 6803.</a> Environmental Microbiology. 18 (2), 486-502 (2016).</li><li>Flores, 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=The+alternative+sigma+factor+SigF+is+a+key+player+in+the+control+of+secretion+mechanisms+in+Synechocystis+sp.+PCC+6803.">The alternative sigma factor SigF is a key player in the control of secretion mechanisms in Synechocystis sp. PCC 6803.</a> Environmental Microbiology. 21 (1), 343-359 (2018).</li><li>Dubois, M., Gilles, K. A., Hamilton, J. K., Rebers, P. A., Smith, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Colorimetric+method+for+determination+of+sugars+and+related+substances.">Colorimetric method for determination of sugars and related substances.</a> Analytical Chemistry. 28 (3), 350-356 (1956).</li><li>Parikh, A., Madamwar, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Partial+characterization+of+extracellular+polysaccharides+from+cyanobacteria.">Partial characterization of extracellular polysaccharides from cyanobacteria.</a> Bioresource Technology. 97 (15), 1822-1827 (2006).</li><li>R&#252;hmann, B., Schmid, J., Sieber, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+to+identify+the+unexplored+diversity+of+microbial+exopolysaccharides.">Methods to identify the unexplored diversity of microbial exopolysaccharides.</a> Frontiers in Microbiology. 6, 565 (2015).</li><li>Pathak, J., Rajneesh, R., Sonker, A. S., Kannaujiya, V. K., Sinha, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyanobacterial+extracellular+polysaccharide+sheath+pigment,+scytonemin:+A+novel+multipurpose+pharmacophore.">Cyanobacterial extracellular polysaccharide sheath pigment, scytonemin: A novel multipurpose pharmacophore.</a> Marine Glycobiology. , 343-358 (2016).</li><li>Nguyen, A. T. B., 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=Performances+of+different+protocols+for+exocellular+polysaccharides+extraction+from+milk+acid+gels:+Application+to+yogurt.">Performances of different protocols for exocellular polysaccharides extraction from milk acid gels: Application to yogurt.</a> Food Chemistry. 239, 742-750 (2018).</li><li>Jamshidian, H., Shojaosadati, S. A., Mousavi, S. M., Soudi, M. 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The authors have nothing to disclose.

To better understand bacterial secretion mechanisms and study the released products, it is of extreme importance to demonstrate the efficient isolation and analysis of the biomolecules present in the extracellular bacterial environment (such as released carbohydrate polymers and proteins).
Cyanobacterial extracellular carbohydrate polymers are extremely complex, mainly due to the number and proportion of different monosaccharides that constitute their composition1. The ...

Cyanobacteria are widely recognized as prolific sources of natural products with promising biotechnological/biomedical applications. Therefore, understanding cyanobacterial secretion mechanisms and optimization of the extraction/recovery methods are essential to implement cyanobacteria as efficient microbial cell factories.
Many cyanobacterial strains are able to produce extracellular polymeric substances (EPS), mainly formed by heteropolysaccharides, that remain associated to the cell surface or are released into the medium1. These released carbohydrate polymers have distinct features compared to those from other bacteria, which make them suitable for a wide range of applications (e.g., antivirals2, immunostimulatory3, antioxidant4, metal-chelating5, emulsifying6, and drug delivery agents7,8). Methodology for the isolation of these polymers largely contributes&#160;not only to improved yield but also to increased purity and the specific physical properties of the polymer obtained9. A vast majority of these methods for isolation of the polymers rely on precipitation strategies from the culture medium that are easily accomplished due to the polymer&#8217;s strong anionic nature9,10. In addition, removal of the solvents used in the precipitation step can be rapidly achieved by evaporation and/or lyophilization. Depending on the foreseen application, different steps can be coupled either after or before polymer precipitation in order to tailor the final product, which include trichloroacetic acid (TCA) treatment, filtration, or size exclusion chromatography (SEC) column purification10.
Cyanobacteria are also able to secrete a wide range of proteins through pathways dependent on membrane transporters (classical)11 or mediated by vesicles (non-classical)12. Therefore, analysis of the cyanobacterial exoproteome constitutes an essential tool, both to understand/manipulate cyanobacterial protein secretion mechanisms and understand the specific extracellular function of these proteins. Reliable isolation and analysis of exoproteomes require the concentration of the extracellular milieu, since the abundance of secreted proteins is relatively low. In addition, other physical or chemical steps (e.g., centrifugation, filtration, or protein precipitation) may optimize the quality of the exoproteome obtained, enriching the protein content13, and avoiding the presence of contaminants (e.g., pigments, carbohydrates, etc.)14,15 or the predominance of intracellular proteins in the samples. However, some of these steps may also restrict the set of proteins that can be detected, leading to a biased analysis.
This work describes efficient protocols for the isolation of released carbohydrate polymers and exoproteomes from cyanobacteria culture media. These protocols can be easily adapted to the study&#8217;s specific objectives and user needs, while maintaining the basic steps presented here.

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	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Dialysis membranes</td>
			<td style="width:191px;">Medicell Membranes Ltd&#160;</td>
			<td style="width:119px;">DTV.12000.07</td>
			<td style="width:777px;">Visking Tubing Size 7, Dia 23.8 mm, Width 39-41 mm 30m Roll&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:307px;">Ethanol 96%</td>
			<td style="width:191px;">AGA - &#193;lcool e G&#233;neros Alimentares, S.A.</td>
			<td style="width:119px;">4.000.02.02.00</td>
			<td>Fermentation ethyl alcohol 96% AGA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">PES Filter 0.2 &#956;m</td>
			<td style="width:191px;">Fisher Scientific, Lda</td>
			<td style="width:119px;">15206869</td>
			<td>Syringe filter polystyrene 33MM 0.2&#181;M STR&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Amicon Ultra-15, Ultracel-3K</td>
			<td style="width:191px;">Merck Millipore Ltd.</td>
			<td style="width:119px;">UFC900324</td>
			<td>Centrifugal filters with a nominal molecular weight cut-off of 3 kDa</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Thermo Scientific&#160;Pierce BCA Protein Assay</td>
			<td style="width:191px;">Fisher Scientific, Lda</td>
			<td style="width:119px;">10741395</td>
			<td>Green-to-blue, precise, detergent-compatible assay reagent to measure total protein concentration</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Brillant Blue G Colloidal Concentrate&#160;</td>
			<td style="width:191px;">Sigma Aldrich Qu&#237;mica SL</td>
			<td style="width:119px;">B2025-1EA</td>
			<td>Coomassie blue&#160;</td>
		</tr>
	</tbody>
</table>

looking outwards: isolation of cyanobacterial released carbohydrate polymers and proteins

Cyanobacteria can actively secrete a wide range of biomolecules into the extracellular environment, such as heteropolysaccharides and proteins. The identification and characterization of these biomolecules can improve knowledge about their secretion pathways and help to manipulate them. Furthermore, some of these biomolecules are also interesting in terms of biotechnological applications. Described here are two protocols for easy and rapid isolation of cyanobacterial released carbohydrate polymers and proteins. The method for isolation of released carbohydrate polymers is based on conventional precipitation techniques of polysaccharides in aqueous solutions using organic solvents. This method preserves the characteristics of the polymer and simultaneously avoids the presence of contaminants from cell debris and culture medium. At the end of the process, the lyophilized polymer is ready to be used or characterized or can be subjected to further rounds of purification, depending on the final intended use. Regarding the isolation of the cyanobacterial exoproteome, the technique is based on the concentration of the cell-free medium after removal of the major contaminants by centrifugation and filtration. This strategy allows for reliable isolation of proteins that reach the extracellular milieu via membrane transporters or outer membrane vesicles. These proteins can be subsequently identified using standard mass spectrometry techniques. The protocols presented here can be applied not only to a wide range of cyanobacteria, but also to other bacterial strains. Furthermore, these procedures can be easily tailored according to the final use of the products, purity degree required, and bacterial strain.

A schematic representation of the method described to extract released carbohydrate polymers from cyanobacterial cultures is depicted in Figure 1. Precipitated polymers from the moderate EPS producer cyanobacterium Synechocystis sp. PCC 6803 and the efficient EPS producer Cyanothece sp. CCY 0110 are shown in Figure 2. In Figure 3, lyophilized polymers with different degrees of contamination are shown, highlighting ...

Watch this Scientific Journal Video about Looking Outwards: Isolation of Cyanobacterial Released Carbohydrate Polymers and Proteins at JoVE.com

Looking Outwards: Isolation of Cyanobacterial Released Carbohydrate Polymers and Proteins

Here, protocols for the isolation of cyanobacterial released carbohydrate polymers and isolation of their exoproteomes are described. Both procedures embody key steps to obtain polymers or proteins with high purity degrees that can be used for further analysis or applications. They can also be easily adapted according to specific user needs.

Cyanobacteria can actively secrete a wide range of biomolecules into the extracellular environment, such as heteropolysaccharides and proteins. The ...

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6.4K Views.  Universidade do Porto. Here, protocols for the isolation of cyanobacterial released carbohydrate polymers and isolation of their exoproteomes are described. Both procedures embody key steps to obtain polymers or proteins with high purity degrees that can be used for further analysis or applications. They can also be easily adapted according to specific user needs.

Video: Looking Outwards: Isolation of Cyanobacterial Released Carbohydrate Polymers and Proteins

High-throughput Screening of Carbohydrate-degrading Enzymes Using Novel Insoluble Chromogenic Substrate Assay Kits

Carbohydrates active enzymes (CAZymes) have multiple roles in vivo and are widely used for industrial processing in the biofuel, textile, detergent, paper and food industries. A deeper understanding of CAZymes is important from both fundamental biology and industrial standpoints. Vast numbers of CAZymes exist in nature (especially in microorganisms) and hundreds of thousands have been cataloged and described in the carbohydrate active enzyme database (CAZy). However, the rate of discovery of putative enzymes has outstripped our ability to biochemically characterize their activities. One reason for this is that advances in genome and transcriptome sequencing, together with associated bioinformatics tools allow for rapid identification of candidate CAZymes, but technology for determining an enzyme's biochemical characteristics has advanced more slowly. To address this technology gap, a novel high-throughput assay kit based on insoluble chromogenic substrates is described here. Two distinct substrate types were produced: Chromogenic Polymer Hydrogel (CPH) substrates (made from purified polysaccharides and proteins) and Insoluble Chromogenic Biomass (ICB) substrates (made from complex biomass materials). Both CPH and ICB substrates are provided in a 96-well high-throughput assay system. The CPH substrates can be made in four different colors, enabling them to be mixed together and thus increasing assay throughput. The protocol describes a 96-well plate assay and illustrates how this assay can be used for screening the activities of enzymes, enzyme cocktails, and broths.

A high-throughput assay for enzyme screening is described. This multiplexed ready-to-use assay kit comprises of pre-chosen Chromogenic Polymer Hydrogel (CPH) substrates and complex Insoluble Chromogenic Biomass (ICB) substrates. Target enzymes are polysaccharide degrading endo-enzymes and proteases.

Carbohydrates active enzymes (CAZymes) have multiple roles in vivo and are widely used for industrial processing in the biofuel, textile, detergent, paper ...

Identification of Plant Ice-binding Proteins Through Assessment of Ice-recrystallization Inhibition and Isolation Using Ice-affinity Purification

Ice-binding proteins (IBPs) belong to a family of stress-induced proteins that are synthesized by certain organisms exposed to subzero temperatures. In plants, freeze damage occurs when extracellular ice crystals grow, resulting in the rupture of plasma membranes and possible cell death. Adsorption of IBPs to ice crystals restricts further growth by a process known as ice-recrystallization inhibition (IRI), thereby reducing cellular damage. IBPs also demonstrate the ability to depress the freezing point of a solution below the equilibrium melting point, a property known as thermal hysteresis (TH) activity. These protective properties have raised interest in the identification of novel IBPs due to their potential use in industrial, medical and agricultural applications. This paper describes the identification of plant IBPs through 1) the induction and extraction of IBPs in plant tissue, 2) the screening of extracts for IRI activity, and 3) the isolation and purification of IBPs. Following the induction of IBPs by low temperature exposure, extracts are tested for IRI activity using a &#39;splat assay&#39;, which allows the observation of ice crystal growth using a standard light microscope. This assay requires a low protein concentration and generates results that are quickly obtained and easily interpreted, providing an initial screen for ice binding activity. IBPs can then be isolated from contaminating proteins by utilizing the property of IBPs to adsorb to ice, through a technique called &#39;ice-affinity purification&#39;. Using cell lysates collected from plant extracts, an ice hemisphere can be slowly grown on a brass probe. This incorporates IBPs into the crystalline structure of the polycrystalline ice. Requiring no a priori biochemical or structural knowledge of the IBP, this method allows for recovery of active protein. Ice-purified protein fractions can be used for downstream applications including the identification of peptide sequences by mass spectrometry and the biochemical analysis of native proteins.

This paper outlines the identification of ice-binding proteins from freeze-tolerant plants through the assessment of ice-recrystallization inhibition activity and subsequent isolation of native IBPs using ice-affinity purification.

Ice-binding proteins (IBPs) belong to a family of stress-induced proteins that are synthesized by certain organisms exposed to subzero temperatures. In ...

Isolation of Intermediate Filament Proteins from Multiple Mouse Tissues to Study Aging-associated Post-translational Modifications

Intermediate filaments (IFs), together with actin filaments and microtubules, form the cytoskeleton &#8211; a critical structural element of every cell. Normal functioning IFs provide cells with mechanical and stress resilience, while a dysfunctional IF cytoskeleton compromises cellular health and has been associated with many human diseases. Post-translational modifications (PTMs) critically regulate IF dynamics in response to physiological changes and under stress conditions. Therefore, the ability to monitor changes in the PTM signature of IFs can contribute to a better functional understanding, and ultimately conditioning, of the IF system as a stress responder during cellular injury. However, the large number of IF proteins, which are encoded by over 70 individual genes and expressed in a tissue-dependent manner, is a major challenge in sorting out the relative importance of different PTMs. To that end, methods that enable monitoring of PTMs on IF proteins on an organism-wide level, rather than for isolated members of the family, can accelerate research progress in this area. Here, we present biochemical methods for the isolation of the total, detergent-soluble, and detergent-resistant fraction of IF proteins from 9 different mouse tissues (brain, heart, lung, liver, small intestine, large intestine, pancreas, kidney, and spleen). We further demonstrate an optimized protocol for rapid isolation of IF proteins by using lysing matrix and automated homogenization of different mouse tissues. The automated protocol is useful for profiling IFs in experiments with high sample volume (such as in disease models involving multiple animals and experimental groups). The resulting samples can be utilized for various downstream analyses, including mass spectrometry-based PTM profiling. Utilizing these methods, we provide new data to show that IF proteins in different mouse tissues (brain and liver) undergo parallel changes with respect to their expression levels and PTMs during aging.

In this method, we present biochemical procedures for rapid and efficient isolation of intermediate filament (IF) proteins from multiple mouse tissues. Isolated IFs can be used to study changes in post-translational modifications by mass spectrometry and other biochemical assays.

Intermediate filaments (IFs), together with actin filaments and microtubules, form the cytoskeleton &#8211; a critical structural element of every cell. ...

Biochemical and Structural Characterization of the Carbohydrate Transport Substrate-binding-protein SP0092

Development of new antimicrobials and vaccines for Streptococcus pneumoniae (pneumococcus) are necessary to halt the rapid rise in multiple resistant strains. Carbohydrate substrate binding proteins (SBPs) represent viable targets for the development of protein-based vaccines and new antimicrobials because of their extracellular localization and the centrality of carbohydrate import for pneumococcal metabolism, respectively. Described here is a rationalized integrated protocol to carry out a comprehensive characterization of SP0092, which can be extended to other carbohydrate SBPs from the pneumococcus and other bacteria. This procedure can aid the structure-based design of inhibitors for this class of proteins. Presented in the first part of this manuscript are protocols for biochemical analysis by thermal shift assay, multi angle light scattering (MALS), and size exclusion chromatography (SEC), which optimize the stability and homogeneity of the sample directed to crystallization trials and so enhance the probability of success. The second part of this procedure describes the characterization of the SBP crystals using a tunable wavelength anomalous diffraction synchrotron beamline, and data collection protocols for measuring data that can be used to resolve the crystallized protein structure.

A streamlined protocol for performing an extensive biochemical and structural characterization of a carbohydrate substrate binding protein from Streptococcus pneumoniae is presented.

Development of new antimicrobials and vaccines for Streptococcus pneumoniae (pneumococcus) are necessary to halt the rapid rise in multiple resistant ...

Analyzing Dynamic Protein Complexes Assembled On and Released From Biolayer Interferometry Biosensor Using Mass Spectrometry and Electron Microscopy

In vivo, proteins are often part of large macromolecular complexes where binding specificity and dynamics ultimately dictate functional outputs. In this work, the pre-endosomal anthrax toxin is assembled and transitioned into the endosomal complex. First, the N-terminal domain of a cysteine mutant lethal factor (LFN) is attached to a biolayer interferometry (BLI) biosensor through disulfide coupling in an optimal orientation, allowing protective antigen (PA) prepore to bind (Kd 1 nM). The optimally oriented LFN-PAprepore complex then binds to soluble capillary morphogenic gene-2 (CMG2) cell surface receptor (Kd 170 pM), resulting in a representative anthrax pre-endosomal complex, stable at pH 7.5. This assembled complex is then subjected to acidification (pH 5.0) representative of the late endosome environment to transition the PAprepore into the membrane inserted pore state. This PApore state results in a weakened binding between the CMG2 receptor and the LFN-PApore and a substantial dissociation of CMG2 from the transition pore. The thio-attachment of LFN to the biosensor surface is easily reversed by dithiothreitol. Reduction on the BLI biosensor surface releases the LFN-PAprepore-CMG2 ternary complex or the acid transitioned LFN-PApore complexes into microliter volumes. Released complexes are then visualized and identified using electron microscopy and mass spectrometry. These experiments demonstrate how to monitor the kinetic assembly/disassembly of specific protein complexes using label-free BLI methodologies and evaluate the structure and identity of these BLI assembled complexes by electron microscopy and mass spectrometry, respectively, using easy-to-replicate sequential procedures.

Here we present a protocol to monitor the assembly and disassembly of the anthrax toxin using biolayer interferometry (BLI). Following assembly/disassembly on the biosensor surface, the large protein complexes are released from the surface for visualization and identification of components of the complexes using electron microscopy and mass spectrometry, respectively.

In vivo, proteins are often part of large macromolecular complexes where binding specificity and dynamics ultimately dictate functional outputs. In this ...

Isolation of Glomeruli and In Vivo Labeling of Glomerular Cell Surface Proteins

Proteinuria results from the disruption of the glomerular filter that is composed of the fenestrated endothelium, glomerular basement membrane, and podocytes with their slit diaphragms. The delicate structure of the glomerular filter, especially the slit diaphragm, relies on the interplay of diverse cell surface proteins. Studying these cell surface proteins has so far been limited to in vitro studies or histologic analysis. Here, we present a murine in vivo biotinylation labeling method, which enables the study of glomerular cell surface proteins under physiologic and pathophysiologic conditions. This protocol contains information on how to perfuse mouse kidneys, isolate glomeruli, and perform endogenous immunoprecipitation of a protein of interest. Semi-quantitation of glomerular cell surface abundance is readily available with this novel method, and all proteins accessible to biotin perfusion and immunoprecipitation can be studied. In addition, isolation of glomeruli with or without biotinylation enables further analysis of glomerular RNA and protein as well as primary glomerular cell culture (i.e., primary podocyte cell culture).

Isolation of Glomeruli and In Vivo Labeling of Glomerular Cell Surface Proteins

Here we present a protocol for murine in vivo labeling of glomerular cell surface proteins with biotin. This protocol contains information on how to perfuse mouse kidneys, isolate glomeruli, and perform endogenous immunoprecipitation of the protein of interest.

Proteinuria results from the disruption of the glomerular filter that is composed of the fenestrated endothelium, glomerular basement membrane, and ...

Fluorescent Silver Staining of Proteins in Polyacrylamide Gels

Silver staining is a colorimetric technique widely used to visualize protein bands in polyacrylamide gels following sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The classic silver stains have certain drawbacks, such as high background staining, poor protein recovery, low reproducibility, a narrow linear dynamic range for quantification, and limited compatibility with mass spectrometry (MS). Now, with the use of a fluorogenic Ag+ probe, TPE-4TA, we developed a fluorescent silver staining method for the total protein visualization in polyacrylamide gels. This new stain avoids the troublesome silver reduction step in traditional silver stains. Moreover, the fluorescent silver stain demonstrates good reproducibility, sensitivity, and linear quantification in protein detection, making it a useful and practical protein gel stain.

Here, we describe a detailed protocol outlining a new fluorescent staining technique for total protein detection in polyacrylamide gels. The protocol utilizes a silver ion-specific fluorescence turn-on probe, which detects Ag+-protein complexes, and eliminates certain limitations of traditional chromogenic silver stains.

Silver staining is a colorimetric technique widely used to visualize protein bands in polyacrylamide gels following sodium dodecyl sulfate-polyacrylamide ...

Interfacial Molecular-level Structures of Polymers and Biomacromolecules Revealed via Sum Frequency Generation Vibrational Spectroscopy

As a second-order nonlinear optical spectroscopy, sum frequency generation (SFG) vibrational spectroscopy has widely been used in investigating various surfaces and interfaces. This non-invasive optical technique can provide the local molecular-level information with monolayer or submonolayer sensitivity. We here are providing experimental methodology on how to selectively detect the buried interface for both macromolecules and biomacromolecules. With this in mind, interfacial secondary structures of silk fibroin and water structures around model short-chain oligonucleotide duplex are discussed. The former shows a chain-chain overlap or spatial confinement effect and the latter shows a protection function against the Ca2+ ions resulting from the chiral spine superstructure of water.

Being comprehensively utilized, sum frequency generation (SFG) vibrational spectroscopy can help to reveal chain conformational order and secondary structural change happening at polymer and biomacromolecule interfaces.

As a second-order nonlinear optical spectroscopy, sum frequency generation (SFG) vibrational spectroscopy has widely been used in investigating various ...

Localization of SUMO-modified Proteins Using Fluorescent Sumo-trapping Proteins

Here we are presenting a novel method to study the sumoylation of proteins and their sub-cellular localization in mammalian cells and nematode oocytes. This method utilizes a recombinant modified SUMO-trapping protein fragment, kmUTAG, derived from the Ulp1 SUMO protease of the stress-tolerant budding yeast Kluyveromyces marxianus. We have adapted the properties of the kmUTAG for the purpose of studying sumoylation in a variety of model systems without the use of antibodies. For the study of SUMO, KmUTAG has several advantages when compared to antibody-based approaches. This stress-tolerant SUMO-trapping reagent is produced recombinantly, it recognizes native SUMO isoforms from many species, and unlike commercially available antibodies it shows reduced affinity for free, unconjugated SUMO. Representative results shown here include the localization of SUMO conjugates in mammalian tissue culture cells and nematode oocytes.

SUMO is an essential and highly conserved, small ubiquitin-like modifier protein. In this protocol we are describing the use of a stress-tolerant recombinant SUMO-trapping protein (kmUTAG) to visualize native, untagged SUMO conjugates and their localization in a variety of cell types.

Here we are presenting a novel method to study the sumoylation of proteins and their sub-cellular localization in mammalian cells and nematode oocytes. ...

Preparation of High-Quality Fermented Fish Product

This protocol provides a method for preparation of industrialized fermented fish product with sturgeon (Aquilaria sinensis) meat product. The procedures were: (1) pretreatment of farmed sturgeon including decapitation, evisceration, skinning-off, cleaning and cutting; (2) marinating fish cubes in 6-12% (w/v) salt solution (1:1, fish cube mass to solution volume); (3) drying fish cubes to a water content of 50-60% by hot air (40-60 &#176;C) or by vacuum; (4) fermentation involving inoculating fish cubes with 0.4-1.6% (w/w) S. cerevisiae in flavor solution to fish cubes and fermenting at 25-35 &#176;C for 6-10 h; (5) sealing fish cubes in vacuum packages with marinating and fermenting solutions; (6) sterilizing at 115-121 &#176;C for 10-20 min. The sturgeon meat product prepared by this method has delicious taste which is mellow and thick, has various types and large amounts of volatile flavor compounds such as alcohols and esters which could mask musty and unpleasant odor from fish, has moderate salt content but good texture properties such as high springiness, gumminess and chewiness, and has bright russet color and attractive appearance. This new technique could also be applied in the processing of other fish to provide convenient fish snack foods which could be stored at room temperature. It is appropriate for both marine and freshwater fish.

The goal of the protocol is to provide an industrialized fish fermentation technique based on inoculation of Saccharomyces cerevisiae.

This protocol provides a method for preparation of industrialized fermented fish product with sturgeon (Aquilaria sinensis) meat product. The procedures ...