Sumoylation of SAE2 C Terminus Regulates SAE Nuclear Localization |
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Authors: | Khue Truong Terry D Lee Baozong Li Yuan Chen |
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Institution: | From the ‡Department of Molecular Medicine and ;§Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010 |
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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. |
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Keywords: | Intracellular Trafficking Post-translational Modification Protein Export Sumo Sumoylation NLS SAE SAE2 SIM SUMO-interacting Motif |
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