title: Sumoylation of SAE2 C terminus regulates SAE nuclear localization.
abstract: SUMOylation occurs predominantly in the nucleus, but non-nuclear proteins can also be SUMOylated. It is unclear how intracellular trafficking of the SUMOylation enzymes is regulated to catalyze SUMOylation in different cellular compartments. Here we report that the SAE2 subunit of human SUMO activation enzyme (SAE) underwent rapid nucleocytoplasmic shuttling and its nuclear accumulation depended on SUMO modification at the C terminus. The SUMOylation sites included three Lys residues on the bipartite nuclear localization sequence (NLS) and two Lys residues outside of but adjacent to the NLS, and their SUMOylation was catalyzed by Ubc9. Because SAE2 forms a tight heterodimer with SAE1 and it controls the trafficking of the heterodimer, this study has identified the mechanism used to localize SAE to the nucleus. Similar mechanisms are likely to exist for other proteins that depend on SUMOylation for nuclear localization.
authors.affiliation: Department of Molecular Medicine, Beckman Research Institute of the City of Hope, Duarte, California 91010, USA.
authors.forename: Khue
authors.initials: K
authors.lastname: Truong
authors.forename: Terry D
authors.initials: TD
authors.lastname: Lee
authors.forename: Baozong
authors.initials: B
authors.lastname: Li
authors.forename: Yuan
authors.initials: Y
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008239:Lysine / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals / Q000737:chemistry / Q000378:metabolism; D021381:Protein Transport; D058207:Sumoylation; D044764:Ubiquitin-Activating Enzymes / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D019913:Nuclear Localization Signals; C470301:UBA2 protein, human; D044764:Ubiquitin-Activating Enzymes; D008239:Lysine