title: Noncovalent binding of small ubiquitin-related modifier (SUMO) protease to SUMO is necessary for enzymatic activities and cell growth.
abstract: SUMO proteases possess two enzymatic activities to hydrolyze the C-terminal region of SUMOs (hydrolase activity) and to remove SUMO from SUMO-conjugated substrates (isopeptidase activity). SUMO proteases bind to SUMOs noncovalently, but the physiological roles of the binding in the functions of SUMO proteases are not well understood. In this study we found that SUMO proteases (Axam, SENP1, and yeast Ulp1) show different preferences for noncovalent binding to various SUMOs (SUMO-1, -2, -3, and yeast Smt3) and that the hydrolase and isopeptidase activities of SUMO proteases are dependent on their binding to SUMOs through salt bridge. Expression of Smt3 suppressed the phenotype of yeast mutant lacking smt3, which exhibits growth arrest, and the binding of Ulp1 to Smt3 was essential for this rescue activity. Although expression of an Smt3 mutant (smt3R64E(GG)), which conjugates to substrate but loses the ability to bind to Ulp1, rescued the phenotype of yeast lacking smt3 partially, the mutant cells showed an increment in the doubling time and a delay of desumoylation of Smt3-conjugated Cdc3. These results indicate that the noncovalent binding of SUMO protease to SUMO through salt bridge is essential for the enzymatic activities and that the balance between sumoylation and desumoylation is important for cell growth control.
authors.affiliation: Department of Biochemistry, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima 734-8551, Japan.
authors.forename: Motomasa
authors.initials: M
authors.lastname: Ihara
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Koyama
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Uchimura
authors.forename: Hisato
authors.initials: H
authors.lastname: Saitoh
authors.forename: Akira
authors.initials: A
authors.lastname: Kikuchi
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D051379:Mice; D051304:Profilins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D011994:Recombinant Proteins; D025842:SUMO-1 Protein / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C086662:CDC3 protein, S cerevisiae; D018797:Cell Cycle Proteins; D051304:Profilins; D011994:Recombinant Proteins; D025842:SUMO-1 Protein; D029701:Saccharomyces cerevisiae Proteins; D010450:Endopeptidases; C404512:SENP1 protein, human; D003546:Cysteine Endopeptidases; C501974:Senp1 protein, mouse; C118083:Ulp1 protease