title: Diversification of SUMO-activating enzyme in Arabidopsis: implications in SUMO conjugation.
abstract: Sumoylation is an essential posttranslational modification that participates in many biological processes including stress responses. However, little is known about the mechanisms that control Small Ubiquitin-like MOdifier (SUMO) conjugation in vivo. We have evaluated the regulatory role of the heterodimeric E1 activating enzyme, which catalyzes the first step in SUMO conjugation. We have established that the E1 large SAE2 and small SAE1 subunits are encoded by one and three genes, respectively, in the Arabidopsis genome. The three paralogs genes SAE1a, SAE1b1, and SAE1b2 are the result of two independent duplication events. Since SAE1b1 and SAE1b2 correspond to two identical copies, only two E1 small subunit isoforms are present in vivo: SAE1a and SAE1b. The E1 heterodimer nuclear localization is modulated by the C-terminal tail of the SAE2 subunit. In vitro, SUMO conjugation rate is dependent on the SAE1 isoform contained in the E1 holoenzyme and our results suggest that downstream steps to SUMO-E1 thioester bond formation are affected. In vivo, SAE1a isoform deletion in T-DNA insertion mutant plants conferred sumoylation defects upon abiotic stress, consistent with a sumoylation defective phenotype. Our results support previous data pointing to a regulatory role of the E1 activating enzyme during SUMO conjugation and provide a novel mechanism to control sumoylation in vivo by diversification of the E1 small subunit.
authors.affiliation: Center for Research in Agricultural Genomics CRAG (CSIC-IRTA-UAB-UB), Edifici CRAG-Campus UAB, Bellaterra (Cerdanyola del Vallés), 08193 Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Castaño-Miquel
authors.forename: Josep
authors.initials: J
authors.lastname: Seguí
authors.forename: Silvia
authors.initials: S
authors.lastname: Manrique
authors.forename: Inês
authors.initials: I
authors.lastname: Teixeira
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Carretero-Paulet
authors.forename: Félix
authors.initials: F
authors.lastname: Atencio
authors.forename: L Maria
authors.initials: LM
authors.lastname: Lois
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001499:Bayes Theorem; D017124:Conserved Sequence; D019143:Evolution, Molecular; D017343:Genes, Plant / Q000235:genetics; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism*; D013312:Stress, Physiological; D013347:Subcellular Fractions / Q000201:enzymology; D058207:Sumoylation; D044764:Ubiquitin-Activating Enzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D020033:Protein Isoforms; D025841:Small Ubiquitin-Related Modifier Proteins; D044764:Ubiquitin-Activating Enzymes
keywords: E1 activating enzyme; abiotic stress; conjugation rate; gene duplication.; regulation; subcellular localization