Rac1 GTPase activates the WAVE regulatory complex through two distinct binding sites

Baoyu Chen, Hui Ting Chou, Chad A Brautigam, Wenmin Xing, Sheng Yang, Lisa Henry, Lynda K. Doolittle, Thomas Walz, Michael K Rosen

Research output: Contribution to journalArticlepeer-review

85 Scopus citations


The Rho GTPase Rac1 activates the WAVE regulatory complex (WRC) to drive Arp2/3 complex-mediated actin polymerization, which underpins diverse cellular processes. Here we report the structure of a WRC-Rac1 complex determined by cryo-electron microscopy. Surprisingly, Rac1 is not located at the binding site on the Sra1 subunit of the WRC previously identified by mutagenesis and biochemical data. Rather, it binds to a distinct, conserved site on the opposite end of Sra1. Biophysical and biochemical data on WRC mutants confirm that Rac1 binds to both sites, with the newly identified site having higher affinity and both sites required for WRC activation. Our data reveal that the WRC is activated by simultaneous engagement of two Rac1 molecules, suggesting a mechanism by which cells may sense the density of active Rac1 at membranes to precisely control actin assembly.

Original languageEnglish (US)
Article numbere29795
StatePublished - Sep 26 2017

ASJC Scopus subject areas

  • Neuroscience(all)
  • Immunology and Microbiology(all)
  • Biochemistry, Genetics and Molecular Biology(all)


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