We thank Dr. Oliver Kerscher for support and advice and members of the Basrai laboratory for their support and comments on the paper. This work was supported by the National Institutes of Health Intramural Research Program.

1. Growth of Yeast Cells
<ol>
	<li>Inoculate yeast cells in 30 ml of YPD (Table 1) in a small flask. Incubate at 30 &#176;C overnight with shaking.</li>
	<li>Dilute the cells to an optical density of 0.2 at 600 nm (OD600 = 0.2) in 50 ml of YPD and incubate at 30 &#176;C with shaking.</li>
	<li>Grow the culture to an optical density of 1.0 at 600 nm (OD600 = 1.0).</li>
	<li>Centrifuge cells for 5 min at 2,000 x g and discard the supernatant.</li>
	<li>Resuspend the cell pellet in 40 ml sterile water and centrifuge for 5 min at 2,000 x g to wash the cells. Discard the supernatant and store the cell pellet at -20 &#176;C.</li>
</ol>
2. Extraction of Proteins
<ol>
	<li>Resuspend cells in 0.5 ml of ice-cold guanidine buffer (Table 1) for pull-down assay using Ni-NTA superflow beads or buffer A (Table 1) for immunoprecipitation. Keep tubes on ice at all times.</li>
	<li>Transfer to 2 ml screw cap tube.</li>
	<li>Add the same volume of glass beads (Table of Materials).</li>
	<li>Bead-beat the cells in a mini bead beater (Table of Materials) for 2 min at room temperature, then place on ice for 2-3 min. Repeat this three times.</li>
	<li>Vortex on high speed at 4 &#176;C for 30-60 min. Check the cells by visualization under the microscope to ensure that the cells are lysed. 
	Note: Lysed cells will appear as dark ghosts and lack a boundary or defined shape. Optimally at least 80% of the cells should be lysed.</li>
	<li>Puncture a hole in the bottom of the tube using a push pin and place in a collection 15 ml conical tube (screw cap should be loose).</li>
	<li>Centrifuge at 1,000 x g for 1 min to collect the lysate.</li>
	<li>Transfer the lysate to a micro centrifuge tube.</li>
	<li>Centrifuge at 15,000 x g for 30 min at 4 &#176;C to collect the extracted proteins.</li>
	<li>Measure the concentration of the extracted proteins using the protein assay kit (Table of Materials) and normalize all extracts to contain the same amount of protein. Bring the total volume to 1 ml with appropriate buffer. 
	Note: Around 5 mg of total protein is obtained from 50 OD600 cells.</li>
	<li>Save 50 &#181;l (250 &#181;g protein if the total protein extracted from step 2.10 is 5 mg) as whole cell extract (WCE). Add 50 &#181;l of 2x Laemmli sample buffer (Table 1) and incubate at 100 &#176;C in a heat block for 3-5 min. Load 10 &#181;l of each sample in a SDS-PAGE gel for Western Blot analysis (Section 5: Western blot analysis).</li>
</ol>
3. Purification of HF-Smt3 Conjugates
<ol>
	<li>Obtain the Ni-NTA superflow beads (Table of Materials) necessary for the experiments (100 &#181;l of beads per sample) by low speed centrifugation (800-1,500 x g) for 1 min. Remove the supernatant.</li>
	<li>Wash beads 5x with 1 ml of PBS (Table of Materials): Invert top-over-bottom until the beads are resuspended, collect beads by low speed centrifugation, and remove the supernatant.</li>
	<li>Suspend beads in 1 ml of guanidine buffer (Table 1) and aliquot them into the number of tubes corresponding to samples to be processed. Collect beads by low speed centrifugation, and remove the supernatant. Mix the beads well by inverting top-over bottom. 
	Note: Mix beads well by inverting top-over bottom.</li>
	<li>For each sample, add 950 &#181;l of the remaining WCE (from Step 2.11: Extraction of proteins) to 100 &#181;l of Ni-NTA superflow beads.</li>
	<li>Incubate on a rocking platform at 4 &#176;C for at least 4 hr or overnight.</li>
	<li>Centrifuge at 800-1,500 x g for 1 min at 4 &#176;C.</li>
	<li>Save 50 &#181;l as supernatant (SUP). Add 50 &#181;l of 2x Laemmli sample buffer and incubate at 100 &#176;C in a heat block for 3-5 min. Load 10 &#181;l of each sample in an SDS-PAGE gel for Western Blot analysis (Section 5: Western blot analysis).</li>
	<li>Wash beads once with 1 ml of guanidine buffer for 5-10 min on a rocking platform.</li>
	<li>Wash beads 5x with 1 ml of breaking buffer (Table 1) for 5-10 min on a rocking platform.</li>
	<li>Resuspend beads in 90 &#181;l of 2x Laemmli sample buffer.</li>
	<li>Add 10 &#181;l of 1 M imidazole. 
	Note: Imidazole helps to dissociate the His-tagged protein from the Ni-NTA beads due to competing interaction between imidazole and the beads.</li>
	<li>Incubate at 100 &#176;C in a heat block for 3-5 min.</li>
	<li>Vortex, then centrifuge at 13,000 x g for 30 sec. Transfer the supernatant to a fresh tube.</li>
	<li>Load 10-20 &#181;l of each sample in an SDS-PAGE gel for Western Blot analysis (Section 5: Western blot analysis). 
	Note: 10-20 &#181;l corresponds to 0.5-1.0 mg of input, if 5 mg of WCE is used.</li>
</ol>
4. Immunoprecipitation of Myc-tagged Kinetochore Proteins
<ol>
	<li>Obtain anti-c-Myc agarose affinity gel antibody (Table of Materials) necessary for the experiments (25 &#181;l of resin per sample) by low speed centrifugation (800-1,500 x g). Remove the supernatant.</li>
	<li>Wash resin 5x with 1 ml of buffer A: Invert top-over-bottom until the resin is resuspended, collect resin by low speed centrifugation, and remove the supernatant.</li>
	<li>Suspend resin in 1 ml of buffer A and aliquot them into the number of tubes corresponding to samples to be processed. Collect resin by low speed centrifugation, and remove the supernatant. 
	Note: Mix the resin well by inverting top-over-bottom.</li>
	<li>Add 950 &#181;l of the remaining WCE (from Step 2.11: Extraction of proteins) to 25 &#181;l of resin.</li>
	<li>Incubate on a rocking platform at 4 &#176;C overnight.</li>
	<li>Centrifuge at 800-1,500 x g for 1 min at 4 &#176;C.</li>
	<li>Save 50 &#181;l as supernatant (SUP). Add 50 &#181;l of 2x Laemmli sample buffer and incubate at 100 &#176;C in a heat block for 3-5 min. Load 10 &#181;l of each sample in an SDS-PAGE gel for Western Blot analysis (Section 5: Western blot analysis).</li>
	<li>Wash resin 5x with 1 ml of buffer A: Invert top-over-bottom until the resin is resuspended, collect resin by low speed centrifugation, and remove the supernatant.</li>
	<li>Resuspend the resin in 100 &#181;l of SUMEB sample buffer (Table 1). 
	Note: SUMEB sample buffer contains 8 M Urea and 1 % SDS (strong denaturing condition).</li>
	<li>Incubate at 100 &#176;C in a heat block for 3-5 min.</li>
	<li>Vortex, then centrifuge at 13,000 x g for 30 sec. Transfer the supernatant to a fresh tube.</li>
	<li>Load 10-20 &#181;l of each sample in an SDS-PAGE gel for Western Blot analysis (Section 5: Western blot analysis). 
	Note: 10-20 &#181;l corresponds to 0.5-1.0 mg of input, if 5 mg of WCE is used.</li>
</ol>
5. Western Blot Analysis
<ol>
	<li>Load the protein extracts on 4-12% Bis-Tris gels (Table of Materials) and perform electrophoresis at 120 V for 90 min (Running buffer: Table of Materials).</li>
	<li>Transfer the proteins from gel to a nitrocellulose membrane (Table of Materials) using a transfer apparatus at 30 V for 90 min (Transfer buffer: Table of Materials).</li>
	<li>Block the membrane in 5% milk/1x TBST (Table1) for 1 hr at room temperature.</li>
	<li>Incubate membrane with primary antibody (Table of Materials) in 5% milk/1x TBST overnight at 4 &#176;C. For primary antibodies, use a dilution of 1:1,000 (anti-Flag and anti-Ub antibodies) or 1:5,000 (anti-Myc antibody).</li>
	<li>Wash membrane 3x for 10 min each with 1x TBST.</li>
	<li>Incubate membrane with secondary antibody (Table of Materials) in 5% milk/1x TBST for 1 hr at room temperature. Use a 1:5,000 dilution of secondary antibodies.</li>
	<li>Wash membrane 3x for 10 min each with 1x TBST.</li>
	<li>Incubate membrane with ECL working solution (Table of Materials) for 5 min.</li>
	<li>Expose the membrane to blue sensitive X-Ray film (Table of Materials) and develop using an automatic developer (Table of Materials).</li>
</ol>

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R., Hochstrasser, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SUMO-1:+Ubiquitin+gains+weight.">SUMO-1: Ubiquitin gains weight.</a> Trends Cell Biol. 7, 408-413 (1997).</li><li>Hewawasam, G., 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=Psh1+is+an+E3+ubiquitin+ligase+that+targets+the+centromeric+histone+variant+Cse4.">Psh1 is an E3 ubiquitin ligase that targets the centromeric histone variant Cse4.</a> Mol Cell. 40, 444-454 (2010).</li><li>Ranjitkar, 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=An+E3+ubiquitin+ligase+prevents+ectopic+localization+of+the+centromeric+histone+H3+variant+via+the+centromere+targeting+domain.">An E3 ubiquitin ligase prevents ectopic localization of the centromeric histone H3 variant via the centromere targeting domain.</a> Mol Cell. 40, 455-464 (2010).</li><li>Au, W. 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=A+novel+role+of+the+N+terminus+of+budding+yeast+histone+H3+variant+Cse4+in+ubiquitin-mediated+proteolysis.">A novel role of the N terminus of budding yeast histone H3 variant Cse4 in ubiquitin-mediated proteolysis.</a> Genetics. 194, 513-518 (2013).</li><li>Akiyoshi, 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=The+Mub1/Ubr2+ubiquitin+ligase+complex+regulates+the+conserved+Dsn1+kinetochore+protein.">The Mub1/Ubr2 ubiquitin ligase complex regulates the conserved Dsn1 kinetochore protein.</a> PLoS Genet. 9, e1003216 (2013).</li><li>Biggins, S., 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+conserved+protein+kinase+Ipl1+regulates+microtubule+binding+to+kinetochores+in+budding+yeast.">The conserved protein kinase Ipl1 regulates microtubule binding to kinetochores in budding yeast.</a> Genes Dev. 13, 532-544 (1999).</li><li>Cheeseman, I. M., 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=Phospho-regulation+of+kinetochore-microtubule+attachments+by+the+Aurora+kinase+Ipl1p.">Phospho-regulation of kinetochore-microtubule attachments by the Aurora kinase Ipl1p.</a> Cell. 111, 163-172 (2002).</li><li>Liu, D., Lampson, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+kinetochore-microtubule+attachments+by+Aurora+B+kinase.">Regulation of kinetochore-microtubule attachments by Aurora B kinase.</a> Biochem Soc Trans. 37, 976-980 (2009).</li><li>Montpetit, B., Hazbun, T. R., Fields, S., Hieter, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sumoylation+of+the+budding+yeast+kinetochore+protein+Ndc10+is+required+for+Ndc10+spindle+localization+and+regulation+of+anaphase+spindle+elongation.">Sumoylation of the budding yeast kinetochore protein Ndc10 is required for Ndc10 spindle localization and regulation of anaphase spindle elongation.</a> J Cell Biol. 174, 653-663 (2006).</li><li>Furth, 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=Exposure+of+bipartite+hydrophobic+signal+triggers+nuclear+quality+control+of+Ndc10+at+the+endoplasmic+reticulum/nuclear+envelope.">Exposure of bipartite hydrophobic signal triggers nuclear quality control of Ndc10 at the endoplasmic reticulum/nuclear envelope.</a> Mol Biol Cell. 22, 4726-4739 (2011).</li><li>Li, L., 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=Anaphase-promoting+complex/cyclosome+controls+HEC1+stability.">Anaphase-promoting complex/cyclosome controls HEC1 stability.</a> Cell Prolif. 44, 1-9 (2011).</li><li>Takahashi, Y., Yong-Gonzalez, V., Kikuchi, Y., Strunnikov, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SIZ1/SIZ2+control+of+chromosome+transmission+fidelity+is+mediated+by+the+sumoylation+of+topoisomerase+II.">SIZ1/SIZ2 control of chromosome transmission fidelity is mediated by the sumoylation of topoisomerase II.</a> Genetics. 172, 783-794 (2006).</li><li>Liu, C., Apodaca, J., Davis, L. E., Rao, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteasome+inhibition+in+wild-type+yeast+Saccharomyces+cerevisiae+cells.">Proteasome inhibition in wild-type yeast Saccharomyces cerevisiae cells.</a> Biotechniques. 42, 158 (2007).</li><li>Kitamura, E., Tanaka, K., Kitamura, Y., Tanaka, T. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetochore+microtubule+interaction+during+S+phase+in+Saccharomyces+cerevisiae.">Kinetochore microtubule interaction during S phase in Saccharomyces cerevisiae.</a> Genes Dev. 21, 3319-3330 (2007).</li><li>Gascoigne, K. E., Cheeseman, I. 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The authors have nothing to disclose.

Epitope tags such as HA, Myc, Flag, and GST are widely used for biochemical analysis of proteins. Construction of strains with HF-Smt3 and Myc-tagged kinetochore proteins, such as Ndc10 and Ndc80, facilitates the detection of PTMs such as sumoylation and ubiquitination. HF-Smt3 pull down assay allows the detection of sumoylated kinetochore proteins, Ndc10 and Ndc80 (Figure 1). The affinity purification protocol and western blot analysis using anti-Flag antibody establish the specificity of interaction be...

Ubiquitination and sumoylation allow the conjugation of ubiquitin and Small Ubiquitin-like MOdifier (SUMO; Smt3 in S. cerevisiae 1) to a target protein, respectively. PTMs of kinetochore proteins affect their cellular levels and protein-protein interactions during different cell cycle phases to ensure faithful chromosome segregation. For example, cellular levels of Cse4/CENP-A and outer kinetochore protein Dsn1 are regulated by ubiquitin-mediated proteolysis for ensuring genome stability 2-5. Destabilization of incorrect kinetochore-microtubule attachments requires the Ipl1/Aurora B kinase, which phosphorylates Dam1 and Ndc80 complexes that directly interact with microtubules 6-8. Despite the identification of over seventy kinetochore proteins, there are very few studies that investigate the modifications of these proteins with PTMs, e.g., ubiquitin and SUMO. A major limitation is the ability to preserve the PTMs during purification and the paucity of custom antibodies for detection of PTMs such as sumoylation, phosphorylation, methylation, and others. Characterization of sumoylated kinetochore proteins Ndc10, Cep3, Bir1, and Ndc80 utilized a custom antibody 9. Additionally, Ndc10 has been implicated as a substrate for ubiquitination 10. Human Hec1 (Ndc80 in S. cerevisiae) is also substrate for ubiquitination, regulated by APC/C-hCdh1 E3 ligase 11. Therefore, Ndc10 and Ndc80 are good candidates for optimization of the protocol to detect both sumoylation and ubiquitination in S. cerevisiae.
To facilitate the identification of sumoylation, we constructed strains that express HF-Smt3 and Myc-tagged Ndc10 or Ndc80. The use of epitope tags (HF: His6-Flag) minimizes the background due to cross-reactivity that is frequently observed in polyclonal serum raised against a candidate protein. We devised a protocol to affinity purify HF-Smt3 conjugates and then used commercial anti-Flag and anti-Myc antibodies to detect the presence of sumolyated Ndc10 and Ndc80 in the purified Smt3 preparation. For ubiquitination, we devised a modified immunoprecipitation protocol that preserves ubiquitination of the Myc-tagged kinetochore proteins and performed western blot analysis with commercial anti-Ub antibody to detect ubiquitination of Ndc10 and Ndc80.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Glass beads</td>
			<td>BioSpec Products</td>
			<td align="right">11079105</td>
			<td>0.5 mm dia.</td>
		</tr>
		<tr>
			<td>Mini beadbeater</td>
			<td>BioSpec Products</td>
			<td>#693</td>
			<td>8 cell disrupter</td>
		</tr>
		<tr>
			<td>Ni-NTA superflow</td>
			<td>Qiagen</td>
			<td align="right">30430</td>
			<td>100 ml</td>
		</tr>
		<tr>
			<td>Protease inhibitor cocktail</td>
			<td>Sigma-Aldrich</td>
			<td>P8215</td>
			<td>1 ml</td>
		</tr>
		<tr>
			<td>Anti-c-Myc agarose affinity gel antbody produced in rabbit</td>
			<td>Sigma-Aldrich</td>
			<td>A7470</td>
			<td>1 ml</td>
		</tr>
		<tr>
			<td>Monoclonal anti-Flag M2 antibody produced in mouse</td>
			<td>Sigma-Aldrich</td>
			<td>F1804</td>
			<td>Primary antibody, dilution 1:1000</td>
		</tr>
		<tr>
			<td>c-Myc antibody (A-14)</td>
			<td>Santa Cruz Biotechnology</td>
			<td>sc-789</td>
			<td>Primary antibody, dilution 1:5000</td>
		</tr>
		<tr>
			<td>Purified mouse antibody monoclonal 9E10</td>
			<td>Covance</td>
			<td>MMS-150P</td>
			<td>Primary antibody, dilution 1:5000</td>
		</tr>
		<tr>
			<td>Ubiquitin (P4G7) monoclonal antibody</td>
			<td>Covance</td>
			<td>MMS-258R</td>
			<td>Primary antibody, dilution 1:1000</td>
		</tr>
		<tr>
			<td>ECL Rabbit IgG, HRP-linked whole Ab</td>
			<td>GE Healthcare Life Sciences</td>
			<td>NA934V</td>
			<td>Secondary antibody, dilution 1:5000</td>
		</tr>
		<tr>
			<td>ECL Mouse IgG, HRP-Linked Whole Ab</td>
			<td>GE Healthcare Life Sciences</td>
			<td>NA931V</td>
			<td>Secondary antibody, dilution 1:5000</td>
		</tr>
		<tr>
			<td>DC protein assay</td>
			<td>Bio-Rad</td>
			<td>500-0116</td>
			<td></td>
		</tr>
		<tr>
			<td>Nitrocellulose membrane</td>
			<td>Novex</td>
			<td>LC2001</td>
			<td>0.45 mm pore size</td>
		</tr>
		<tr>
			<td>NuPAGE 4-12% Bis-Tris Protein Gels</td>
			<td>Novex</td>
			<td>NP0321BOX</td>
			<td>1.0 mm, 10 well</td>
		</tr>
		<tr>
			<td>NuPAGE MES SDS Running Buffer</td>
			<td>Novex</td>
			<td>NP0002</td>
			<td>20x</td>
		</tr>
		<tr>
			<td>NuPAGE Transfer Buffer</td>
			<td>Novex</td>
			<td>NP0006-1</td>
			<td>20x</td>
		</tr>
		<tr>
			<td>SuperSignal West Pico Chemiluminescent Substrate</td>
			<td>Thermo Scientific</td>
			<td align="right">34078</td>
			<td></td>
		</tr>
		<tr>
			<td>10x PBS pH7.4</td>
			<td>GIBCO</td>
			<td>70011-044</td>
			<td></td>
		</tr>
		<tr>
			<td>Blue sensitive X-Ray film</td>
			<td>Dbio</td>
			<td>DBOF30003</td>
			<td></td>
		</tr>
		<tr>
			<td>Automatic developer</td>
			<td>Kodak</td>
			<td>M35AX-OMAT</td>
			<td></td>
		</tr>
		<tr>
			<td>Nocodazole</td>
			<td>Sigma-Aldrich</td>
			<td>M1404</td>
			<td>50 mg</td>
		</tr>
		<tr>
			<td>MG-132</td>
			<td>Selleck Chemicals</td>
			<td>S2619</td>
			<td>25 mg</td>
		</tr>
	</tbody>
</table>

protein purification technique that allows detection of sumoylation and ubiquitination of budding yeast kinetochore proteins ndc10 and ndc80

Post-translational Modifications (PTMs), such as phosphorylation, methylation, acetylation, ubiquitination, and sumoylation, regulate the cellular function of many proteins. PTMs of kinetochore proteins that associate with centromeric DNA mediate faithful chromosome segregation to maintain genome stability. Biochemical approaches such as mass spectrometry and western blot analysis are most commonly used for identification of PTMs. Here, a protein purification method is described that allows the detection of both sumoylation and ubiquitination of the kinetochore proteins, Ndc10 and Ndc80, in Saccharomyces cerevisiae. A strain that expresses polyhistidine-Flag-tagged Smt3 (HF-Smt3) and Myc-tagged Ndc10 or Ndc80 was constructed and used for our studies. For detection of sumoylation, we devised a protocol to affinity purify His-tagged sumoylated proteins by using nickel beads and used western blot analysis with anti-Myc antibody to detect sumoylated Ndc10 and Ndc80. For detection of ubiquitination, we devised a protocol for immunoprecipitation of Myc-tagged proteins and used western blot analysis with anti-Ub antibody to show that Ndc10 and Ndc80 are ubiquitinated. Our results show that epitope tagged-protein of interest in the His-Flag tagged Smt3 strain facilitates the detection of multiple PTMs. Future studies should allow exploitation of this technique to identify and characterize protein interactions that are dependent on a specific PTM.

To detect sumoylation of kinetochore proteins Ndc80 and Ndc10, strains with HF-Smt3 and Myc-tagged kinetochore proteins (Ndc80 or Ndc10) were constructed (Table 2), as previously described 9,12. HF-Smt3 conjugates were affinity purified using Ni-NTA beads. Western blot analysis of purified HF-Smt3 with an anti-Flag antibody allowed detection of sumoylated forms of SUMO substrates that were absent in the control strain without HF-Smt3 (Figure 1A and 1B, left pa...

Watch this Scientific Journal Video about Protein Purification Technique that Allows Detection of Sumoylation and Ubiquitination of Budding Yeast Kinetochore Proteins Ndc10 and Ndc80 at JoVE.com

Protein Purification Technique that Allows Detection of Sumoylation and Ubiquitination of Budding Yeast Kinetochore Proteins Ndc10 and Ndc80

This manuscript describes the detection of sumoylation and ubiquitination of kinetochore proteins, Ndc10 and Ndc80, in the budding yeast Saccharomyces cerevisiae.

Post-translational Modifications (PTMs), such as phosphorylation, methylation, acetylation, ubiquitination, and sumoylation, regulate the cellular ...

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12.0K Views.  National Cancer Institute, National Institute of Health. This manuscript describes the detection of sumoylation and ubiquitination of kinetochore proteins, Ndc10 and Ndc80, in the budding yeast Saccharomyces cerevisiae.

Video: Protein Purification Technique that Allows Detection of Sumoylation and Ubiquitination of Budding Yeast Kinetochore Proteins Ndc10 and Ndc80

Measuring Replicative Life Span in the Budding Yeast

Aging is a degenerative process characterized by a progressive deterioration of cellular components and organelles resulting in mortality. The budding yeast Saccharomyces cerevisiae has been used extensively to study the biology of aging, and several determinants of yeast longevity have been shown to be conserved in multicellular eukaryotes, including worms, flies, and mice 1. Due to the lack of easily quantified age-associated phenotypes, aging in yeast has been assayed almost exclusively by measuring the life span of cells in different contexts, with two different life span paradigms in common usage 2. Chronological life span refers to the length of time that a mother cell can survive in a non-dividing, quiescence-like state, and is proposed to serve as a model for aging of post-mitotic cells in multicellular eukaryotes. Replicative life span, in contrast, refers the number of daughter cells produced by a mother cell prior to senescence, and is thought to provide a model of aging in mitotically active cells. Here we present a generalized protocol for measuring the replicative life span of budding yeast mother cells. The goal of the replicative life span assay is to determine how many times each mother cell buds. The mother and daughter cells can be easily differentiated by an experienced researcher using a standard light microscope (total magnification 160X), such as the Zeiss Axioscope 40 or another comparable model. Physical separation of daughter cells from mother cells is achieved using a manual micromanipulator equipped with a fiber-optic needle. Typical laboratory yeast strains produce 20-30 daughter cells per mother and one life span experiment requires 2-3 weeks.

In this article we present a general protocol for measuring the replicative life span of yeast mother cells.

Aging is a degenerative process characterized by a progressive deterioration of cellular components and organelles resulting in mortality. The budding ...

Detection of Protein Ubiquitination

Ubiquitination, the covalent attachment of the polypeptide ubiquitin to target proteins, is a key posttranslational modification carried out by a set of three enzymes. They include ubiquitin-activating enzyme E1, ubiquitin-conjugating enzyme E2, and ubiquitin ligase E3. Unlike to E1 and E2, E3 ubiquitin ligases display substrate specificity. On the other hand, numerous deubiquitylating enzymes have roles in processing polyubiquitinated proteins. Ubiquitination can result in change of protein stability, cellular localization, and biological activity. Mutations of genes involved in the ubiquitination/deubiquitination pathway or altered ubiquitin system function are associated with many different human diseases such as various types of cancer, neurodegeneration, and metabolic disorders. The detection of altered or normal ubiquitination of target proteins may provide a better understanding on the pathogenesis of these diseases. &nbsp;Here, we describe protocols to detect protein ubiquitination in cultured cells in vivo and test tubes in vitro. These protocols are also useful to detect other ubiquitin-like small molecule modification such as sumolyation and neddylation.

Ubiquitination is a key posttranslational modification carried out by a set of three enzymes. Mutations of genes involved in this modification are associated with many different human diseases. Here, we describe protocols to detect protein ubiquitination in cultured cells in vivo and test tubes in vitro.

Ubiquitination, the covalent attachment of the polypeptide ubiquitin to target proteins, is a key posttranslational modification carried out by a set of ...

Staining of Proteins in Gels with Coomassie G-250 without Organic Solvent and Acetic Acid

In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents (Methanol, Ethanol or 2-Propanol) and acetic acid are used for fixation, staining and destaining of proteins in a gel after SDS-PAGE. To speed up the procedure, heating the staining solution in the microwave oven for a short time is frequently used. This usually results in evaporation of toxic or hazardous Methanol, Ethanol or 2-Propanol and a strong smell of acetic acid in the lab which should be avoided due to safety considerations. In a protocol originally published in two patent applications by E.M. Wondrak (US2001046709 (A1), US6319720 (B1)), an alternative composition of the staining solution is described in which no organic solvent or acid is used. The CBB is dissolved in bidistilled water (60-80mg of CBB G-250 per liter) and 35 mM HCl is added as the only other compound in the staining solution. The CBB staning of the gel is done after SDS-PAGE and thorough washing of the gel in bidistilled water. By heating the gel during the washing and staining steps, the process can be finished faster and no toxic or hazardous compunds are evaporating. The staining of proteins occurs already within 1 minute after heating the gel in staining solution and is fully developed after 15-30 min with a slightly blue background that is destained completely by prolonged washing of the stained gel in bidistilled water, without affecting the stained protein bands.

A short protocol for protein staining with Coomassie Brilliant Blue (CBB) G-250 in polyacrylamide gels is described without using organic solvents or acetic acid as in the classical staining procedures with CBB.

In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents ...

Purification of Mitochondria from Yeast Cells

Mitochondria are the main site of ATP production during aerobic metabolism in eukaryotic non-photosynthetic cells1. These complex organelles also play essential roles in apoptotic cell death2, cell survival3, mammalian development4, neuronal development and function4, intracellular signalling5, and longevity regulation6. Our understanding of these complex biological processes controlled by mitochondria relies on robust methods for assessing their morphology, their protein and lipid composition, the integrity of their DNA, and their numerous vital functions. The budding yeast Saccharomyces cerevisiae, a genetically and biochemically manipulable unicellular eukaryote with annotated genome and well-defined proteome, is a valuable model for studying the molecular and cellular mechanisms underlying essential biological functions of mitochondria. For these types of studies, it is crucial to have highly pure mitochondria. Here we present a detailed description of a rapid and effective method for purification of yeast mitochondria. This method enables the isolation of highly pure mitochondria that are essentially free of contamination by other organelles and retain their structural and functional integrity after their purification. Mitochondria purified by this method are suitable for cell-free reconstitution of essential mitochondrial processes and can be used for the analysis of mitochondrial structure and functions, mitochondrial proteome and lipidome, and mitochondrial DNA.

We describe a rapid and effective method for purification of mitochondria from the yeast Saccharomyces cerevisiae. This method enables the high-yield isolation of pure mitochondria that are essentially free of contamination by other organelles and retain their structural and functional integrity after their purification.

Mitochondria are the main site of ATP production during aerobic metabolism in eukaryotic non-photosynthetic cells1. These complex organelles also play ...

Analysis of the Development of a Morphological Phenotype as a Function of Protein Concentration in Budding Yeast

Gene deletion and protein overexpression are common methods for studying functions of proteins. In this article, we describe a protocol for analysis of phenotype development as a function of protein concentration at population and single-cell levels in Saccharomyces cerevisiae. Although this protocol is based on the overexpression of a protein, it can easily be adapted for morphological phenotypes dependent on suppression of protein expression. Our lab is interested in studying the signaling properties of the endocytic adaptor protein epsin. To that purpose we used a dominant negative approach in which we over-expressed the conserved Epsin N-Terminal Homology (ENTH) domain in order to interfere with the functions of endogenous epsin-2 (Ent2 or YLR206W). We observed that overexpression of the ENTH domain of Ent2 (ENTH2) in wild type cells led to a cell division defect that is dependent on the mislocalization of a family of scaffolding proteins, septins.

Gene deletion and protein overexpression are common methods for studying functions of proteins. In this article, we describe a protocol for analysis of phenotype development as a function of protein concentration at population and single-cell levels in Saccharomyces cerevisiae.

Gene deletion and protein overexpression are common methods for studying functions of proteins. In this article, we describe a protocol for analysis of ...

Purification of Hsp104, a Protein Disaggregase

Hsp104 is a hexameric AAA+ protein1 from yeast, which couples ATP hydrolysis to protein disaggregation2-10 (Fig. 1). This activity imparts two key selective advantages. First, renaturation of disordered aggregates by Hsp104 empowers yeast survival after various protein-misfolding stresses, including heat shock3,5,11,12. Second, remodeling of cross-beta amyloid fibrils by Hsp104 enables yeast to exploit myriad prions (infectious amyloids) as a reservoir of beneficial and heritable phenotypic variation13-22. Remarkably, Hsp104 directly remodels preamyloid oligomers and amyloid fibrils, including those comprised of the yeast prion proteins Sup35 and Ure223-30. This amyloid-remodeling functionality is a specialized facet of yeast Hsp104. The E. coli orthologue, ClpB, fails to remodel preamyloid oligomers or amyloid fibrils26,31,32.
Hsp104 orthologues are found in all kingdoms of life except, perplexingly, animals. Indeed, whether animal cells possess any enzymatic system that couples protein disaggregation to renaturation (rather than degradation) remains unknown33-35. Thus, we and others have proposed that Hsp104 might be developed as a therapeutic agent for various neurodegenerative diseases connected with the misfolding of specific proteins into toxic preamyloid oligomers and amyloid fibrils4,7,23,36-38. There are no treatments that directly target the aggregated species associated with these diseases. Yet, Hsp104 dissolves toxic oligomers and amyloid fibrils composed of alpha-synuclein, which are connected with Parkinson's Disease23 as well as amyloid forms of PrP39. Importantly, Hsp104 reduces protein aggregation and ameliorates neurodegeneration in rodent models of Parkinson's Disease23 and Huntington's disease38. Ideally, to optimize therapy and minimize side effects, Hsp104 would be engineered and potentiated to selectively remodel specific aggregates central to the disease in question4,7. However, the limited structural and mechanistic understanding of how Hsp104 disaggregates such a diverse repertoire of aggregated structures and unrelated proteins frustrates these endeavors30,40-42.
To understand the structure and mechanism of Hsp104, it is essential to study the pure protein and reconstitute its disaggregase activity with minimal components. Hsp104 is a 102kDa protein with a pI of ~5.3, which hexamerizes in the presence of ADP or ATP, or at high protein concentrations in the absence of nucleotide43-46. Here, we describe an optimized protocol for the purification of highly active, stable Hsp104 from E. coli. The use of E. coli allows simplified large-scale production and our method can be performed quickly and reliably for numerous Hsp104 variants. Our protocol increases Hsp104 purity and simplifies His6-tag removal compared to a previous purification method from E. coli47. Moreover, our protocol is more facile and convenient than two more recent protocols26,48.

Here, we describe a protocol for the purification of highly active Hsp104, a hexameric AAA+ protein from yeast, which couples ATP hydrolysis to protein disaggregation. This scheme exploits a His6-tagged construct for affinity purification from E. coli followed by anion-exchange chromatography, His6-tag removal with TEV protease, and size-exclusion chromatography.

Hsp104 is a hexameric AAA+ protein1 from yeast, which couples ATP hydrolysis to protein disaggregation2-10 (Fig. 1). This activity imparts two key ...

Chromatographic Purification of Highly Active Yeast Ribosomes

Eukaryotic ribosomes are much more labile as compared to their eubacterial and archael counterparts, thus posing a significant challenge to researchers. Particularly troublesome is the fact that lysis of cells releases a large number of proteases and nucleases which can degrade ribosomes. Thus, it is important to separate ribosomes from these enzymes as quickly as possible. Unfortunately, conventional differential ultracentrifugation methods leaves ribosomes exposed to these enzymes for unacceptably long periods of time, impacting their structural integrity and functionality. To address this problem, we utilize a chromatographic method using a cysteine charged Sulfolink resin. This simple and rapid application significantly reduces co-purifying proteolytic and nucleolytic activities, producing high yields of intact, highly biochemically active yeast ribosomes. We suggest that this method should also be applicable to mammalian ribosomes. The simplicity of the method, and the enhanced purity and activity of chromatographically purified ribosome represents a significant technical advancement for the study of eukaryotic ribosomes.

Contamination of preparations of eukaryotic ribosomes purified by traditional methods by co-purifying nucleases and proteases negatively impacts on downstream biochemical and structural analyses. A rapid and simple chromatographic purification method is used to solve this problem using yeast ribosomes as a model system.

Eukaryotic ribosomes are much more labile as compared to their eubacterial and archael counterparts, thus posing a significant challenge to researchers.  ...

Acquiring Fluorescence Time-lapse Movies of Budding Yeast and Analyzing Single-cell Dynamics using GRAFTS

Fluorescence time-lapse microscopy has become a powerful tool in the study of many biological processes at the single-cell level. In particular, movies depicting the temporal dependence of gene expression provide insight into the dynamics of its regulation; however, there are many technical challenges to obtaining and analyzing fluorescence movies of single cells. We describe here a simple protocol using a commercially available microfluidic culture device to generate such data, and a MATLAB-based, graphical user interface (GUI) -based software package to quantify the fluorescence images. The software segments and tracks cells, enables the user to visually curate errors in the data, and automatically assigns lineage and division times. The GUI further analyzes the time series to produce whole cell traces as well as their first and second time derivatives. While the software was designed for S. cerevisiae, its modularity and versatility should allow it to serve as a platform for studying other cell types with few modifications.

We present a simple protocol to obtain fluorescence microscopy movies of growing yeast cells, and a GUI-based software package to extract single-cell time series data. The analysis includes automated lineage and division time assignment integrated with visual inspection and manual curation of tracked data.

Fluorescence time-lapse microscopy has become a powerful tool in the study of many biological processes at the single-cell level. In particular, movies ...

Budding Yeast Protein Extraction and Purification for the Study of Function, Interactions, and Post-translational Modifications

Homogenization by bead beating is a fast and efficient way to release DNA, RNA, proteins, and metabolites from budding yeast cells, which are notoriously hard to disrupt. Here we describe the use of a bead mill homogenizer for the extraction of proteins into buffers optimized to maintain the functions, interactions and post-translational modifications of proteins. Logarithmically growing cells expressing the protein of interest are grown in a liquid growth media of choice. The growth media may be supplemented with reagents to induce protein expression from inducible promoters (e.g. galactose), synchronize cell cycle stage (e.g. nocodazole), or inhibit proteasome function (e.g. MG132). Cells are then pelleted and resuspended in a suitable buffer containing protease and/or phosphatase inhibitors and are either processed immediately or frozen in liquid nitrogen for later use. Homogenization is accomplished by six cycles of 20 sec&#160;bead-beating (5.5 m/sec), each followed by one minute incubation on ice. The resulting homogenate is cleared by centrifugation and small particulates can be removed by filtration. The resulting cleared whole cell extract (WCE) is precipitated using 20% TCA for direct analysis of total proteins by SDS-PAGE followed by Western blotting. Extracts are also suitable for affinity purification of specific proteins, the detection of post-translational modifications, or the analysis of co-purifying proteins. As is the case for most protein purification protocols, some enzymes and proteins may require unique conditions or buffer compositions for their purification and others may be unstable or insoluble under the conditions stated. In the latter case, the protocol presented may provide a useful starting point to empirically determine the best bead-beating strategy for protein extraction and purification. We show the extraction and purification of an epitope-tagged SUMO E3 ligase, Siz1, a cell cycle regulated protein that becomes both sumoylated and phosphorylated, as well as a SUMO-targeted ubiquitin ligase subunit, Slx5.

The preparation of high quality yeast cell extracts is a necessary first step in the analysis of individual proteins or entire proteomes. Here we describe a fast, efficient, and reliable homogenization protocol for budding yeast cells that has been optimized to preserve protein functions, interactions, and post-translational modifications.

Homogenization by bead beating is a fast and efficient way to release DNA, RNA, proteins, and metabolites from budding yeast cells, which are notoriously ...

Green Fluorescent Protein-based Expression Screening of Membrane Proteins in Escherichia coli

The production of recombinant membrane proteins for structural and functional studies remains technically challenging due to low levels of expression and the inherent instability of many membrane proteins once solubilized in detergents. A protocol is described that combines ligation independent cloning of membrane proteins as GFP fusions with expression in Escherichia coli detected by GFP fluorescence. This enables the construction and expression screening of multiple membrane protein/variants to identify candidates suitable for further investment of time and effort. The GFP reporter is used in a primary screen of expression by visualizing GFP fluorescence following SDS polyacrylamide gel electrophoresis (SDS-PAGE). Membrane proteins that show both a high expression level with minimum degradation as indicated by the absence of free GFP, are selected for a secondary screen. These constructs are scaled and a total membrane fraction prepared and solubilized in four different detergents. Following ultracentrifugation to remove detergent-insoluble material, lysates are analyzed by fluorescence detection size exclusion chromatography (FSEC). Monitoring the size exclusion profile by GFP fluorescence provides information about the mono-dispersity and integrity of the membrane proteins in different detergents. Protein: detergent combinations that elute with a symmetrical peak with little or no free GFP and minimum aggregation are candidates for subsequent purification. Using the above methodology, the heterologous expression in E. coli of SED (shape, elongation, division, and sporulation) proteins from 47 different species of bacteria was analyzed. These proteins typically have ten transmembrane domains and are essential for cell division. The results show that the production of the SEDs orthologues in E. coli was highly variable with respect to the expression levels and integrity of the GFP fusion proteins. The experiment identified a subset for further investigation.

Green Fluorescent Protein-based Expression Screening of Membrane Proteins in Escherichia coli

A streamlined approach to screening for the expression of recombinant membrane proteins in Escherichia coli based on fusion to green fluorescent protein is presented.

The production of recombinant membrane proteins for structural and functional studies remains technically challenging due to low levels of expression and ...