1 Department of Bioengineering, McGill University, Montreal, QC, Canada, H3A 0G4.
2 Department of Biology, Concordia University, Montreal, QC, Canada, H4B 1R6.

Importin-binding mediates the intramolecular regulation of anillin during cytokinesis.

Mol Biol Cell. 2020 Apr 02;:mbcE20010006

Authors: Beaudet D, Pham N, Skaik N, Piekny A

Abstract

Cytokinesis occurs by the ingression of an actomyosin ring that cleaves a cell into two daughters. This process is tightly controlled to avoid aneuploidy, and we previously showed that active Ran coordinates ring positioning with chromatin. Active Ran is high around chromatin, and forms an inverse gradient to cargo-bound importins. We found that the ring component anillin contains a nuclear localization signal (NLS) that binds to importin and is required for its function during cytokinesis. Here we reveal the mechanism whereby importin-binding favors a conformation required for anillin's recruitment to the equatorial cortex. Active RhoA binds to the RhoA-binding domain (RBD) causing an increase in accessibility of the nearby C2 domain containing the NLS. Importin-binding subsequently stabilizes a conformation that favors interactions for cortical recruitment. In addition to revealing a novel mechanism for the importin-mediated regulation of a cortical protein, we also show how importin-binding positively regulates protein function.

PMID: 32238082 [PubMed - as supplied by publisher]