Structure of Importin13-Ubc9 complex: nuclear import and release of a key regulator of sumoylation.

ABSTRACT: Importin13 (Imp13) is an unusual β-karyopherin that is able to both import and export cargoes in and out of the nucleus. In the cytoplasm, Imp13 associates with different cargoes such as Mago-Y14 and Ubc9, and facilitates their import into the nucleus where RanGTP binding promotes the release of the cargo. In this study, we present the 2.8 Å resolution crystal structure of Imp13 in complex with the SUMO E2-conjugating enzyme, Ubc9. The structure shows an uncommon mode of cargo-karyopherin recognition with Ubc9 binding at the N-terminal portion of Imp13, occupying the entire RanGTP-binding site. Comparison of the Imp13-Ubc9 complex with Imp13-Mago-Y14 shows the remarkable plasticity of Imp13, whose conformation changes from a closed ring to an open superhelix when bound to the two different

SUBMITTER: Grunwald M 

PROVIDER: S-EPMC3025465 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature