Dataset Information

The small ubiquitin-like modifier (SUMO) and SUMO-conjugating system of Chlamydomonas reinhardtii.

ABSTRACT: The availability of the complete DNA sequence of the Chlamydomonas reinhardtii genome and advanced computational biology tools has allowed elucidation and study of the small ubiquitin-like modifier (SUMO) system in this unicellular photosynthetic alga and model eukaryotic cell system. SUMO is a member of a ubiquitin-like protein superfamily that is covalently attached to target proteins as a post-translational modification to alter the localization, stability, and/or function of the target protein in response to changes in the cellular environment. Three SUMO homologs (CrSUMO96, CrSUMO97, and CrSUMO148) and three novel SUMO-related proteins (CrSUMO-like89A, CrSUMO-like89B, and CrSUMO-like90) were found by diverse gene predictions, hidden Markov models, and database search tools inferring from Homo sapiens, Saccharomyces cerevisiae, and Arabidopsis thaliana SUMOs. Among them, CrSUMO96, which can be recognized by the A. thaliana anti-SUMO1 antibody, was studied in detail. Free CrSUMO96 was purified by immunoprecipitation and identified by mass spectrometry analysis. A SUMO-conjugating enzyme (SCE) (E2, Ubc9) in C. reinhardtii was shown to be functional in an Escherichia coli-based in vivo chimeric SUMOylation system. Antibodies to CrSUMO96 recognized free and conjugated forms of CrSUMO96 in Western blot analysis of whole-cell extracts and nuclear localized SUMOylated proteins with in situ immunofluorescence. Western blot analysis showed a marked increase in SUMO conjugated proteins when the cells were subjected to environmental stresses, such as heat shock and osmotic stress. Related analyses revealed multiple potential ubiquitin genes along with two Rub1 genes and one Ufm1 gene in the C. reinhardtii genome.

SUBMITTER: Wang Y

PROVIDER: S-EPMC2390597 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature

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The small ubiquitin-like modifier (SUMO) and SUMO-conjugating system of Chlamydomonas reinhardtii.

Wang Ying Y Ladunga Istvan I Miller Amy R AR Horken Kempton M KM Plucinak Thomas T Weeks Donald P DP Bailey Cheryl P CP

Genetics 20080501 1

The availability of the complete DNA sequence of the Chlamydomonas reinhardtii genome and advanced computational biology tools has allowed elucidation and study of the small ubiquitin-like modifier (SUMO) system in this unicellular photosynthetic alga and model eukaryotic cell system. SUMO is a member of a ubiquitin-like protein superfamily that is covalently attached to target proteins as a post-translational modification to alter the localization, stability, and/or function of the target prote ...[more]

PMID: 18493050

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Project description:Post-translational protein modifications (PTMs) including small chemical groups and small proteins, belonging to the ubiquitin family, are essential for virtually all cellular processes. In addition to modification by a single PTM, proteins can be modified by a combination of different modifiers, which are able to influence each other. Because little is known about crosstalk among different ubiquitin family members, we developed an improved method enabling identification of co-modified proteins on a system-wide level using mass spectrometry. We focused on the role of crosstalk between SUMO and ubiquitin during proteasomal degradation. Using two complementary approaches, we identified 498 proteins to be significantly co-modified by SUMO and ubiquitin upon MG132 treatment. These targets included many enzymatic components of PTM machinery, involved in SUMOylation and ubiquitylation, but also phosphorylation, methylation and acetylation, revealing a highly complex interconnected network of crosstalk among different PTMs. In addition, various other biological processes were found to be significantly enriched within the group of co-modified proteins, including transcription, DNA repair and the cell cycle. Interestingly, the latter group mostly consisted of proteins involved in mitosis, including a subset of chromosome segregation regulators. We hypothesize that group modification by SUMO-targeted ubiquitin ligases regulates the stability of the identified subset of mitotic proteins, which ensures proper chromosome segregation. The mitotic regulators KIF23 and MIS18BP1 were verified to be co-modified by SUMO and ubiquitin on inhibition of the proteasome and subsequently identified as novel RNF4 targets. Both modifications on MIS18BP1 were observed to increase simultaneously during late mitosis, whereas the total protein level decreased immediately afterward. These results confirm the regulation of MIS18BP1 via SUMO-ubiquitin crosstalk during mitosis. Combined, our work highlights extensive crosstalk between SUMO and ubiquitin, providing a resource for further unraveling of SUMO-ubiquitin crosstalk.

Dataset Information

The small ubiquitin-like modifier (SUMO) and SUMO-conjugating system of Chlamydomonas reinhardtii.

Publications

The small ubiquitin-like modifier (SUMO) and SUMO-conjugating system of Chlamydomonas reinhardtii.

Similar Datasets

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