title: The ubiquitin-like proteins SMT3 and SUMO-1 are conjugated by the UBC9 E2 enzyme.
abstract: The ubiquitin-like protein SMT3 from Saccharomyces cerevisiae and SUMO-1, its mammalian homolog, can be covalently attached to other proteins posttranslationally. Conjugation of ubiquitin requires the activities of ubiquitin-activating (E1) and -conjugating (E2) enzymes and proceeds via thioester-linked enzyme-ubiquitin intermediates. Herein we show that UBC9, one of the 13 different E2 enzymes from yeast, is required for SMT3 conjugation in vivo. Moreover, recombinant yeast and mammalian UBC9 enzymes were found to form thioester complexes with SMT3 and SUMO-1, respectively. This suggests that UBC9 functions as an E2 in a SMT3/SUMO-1 conjugation pathway analogous to ubiquitin-conjugating enzymes. The role of yeast UBC9 in cell cycle progression may thus be mediated through its SMT3 conjugation activity.
authors.affiliation: Deutsches Krebsforschungszentrum, Heidelberg, Germany.
authors.forename: S E
authors.initials: SE
authors.lastname: Schwarz
authors.forename: K
authors.initials: K
authors.lastname: Matuschewski
authors.forename: D
authors.initials: D
authors.lastname: Liakopoulos
authors.forename: M
authors.initials: M
authors.lastname: Scheffner
authors.forename: S
authors.initials: S
authors.lastname: Jentsch
mesh_terms: D005656:Fungal Proteins / Q000378:metabolism*; D008025:Ligases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D012097:Repressor Proteins / Q000378:metabolism*; D025842:SUMO-1 Protein; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D013379:Substrate Specificity; D044763:Ubiquitin-Conjugating Enzymes; D014452:Ubiquitins / Q000378:metabolism*; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: D005656:Fungal Proteins; D012097:Repressor Proteins; C099362:SMT3 protein, S cerevisiae; D025842:SUMO-1 Protein; D029701:Saccharomyces cerevisiae Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D014452:Ubiquitins; D044763:Ubiquitin-Conjugating Enzymes; D008025:Ligases; D000098843:Ubiquitin-Conjugating Enzyme UBC9