PMID: 30853411

Authors:

Kukimoto-Niino M, Tsuda K, Ihara K, Mishima-Tsumagari C, Honda K, Ohsawa N, Shirouzu M

Title:

Structural Basis for the Dual Substrate Specificity of DOCK7 Guanine Nucleotide Exchange Factor.

Journal:

Structure. 2019 Feb 16. pii: S0969-2126(19)30045-0. doi:, 10.1016/j.str.2019.02.001.

Abstract:

The Dedicator Of CytoKinesis (DOCK) family of atypical guanine nucleotide exchange factors activates the Rho family GTPases Rac and/or Cdc42 through DOCK homology region 2 (DHR-2). Previous structural analyses of the DHR-2 domains of DOCK2 and DOCK9 have shown that they preferentially bind Rac1 and Cdc42, respectively; however, the molecular mechanism by which DHR-2 distinguishes between these GTPases is unclear. Here we report the crystal structure of the Cdc42-bound form of the DOCK7 DHR-2 domain showing dual specificity for Rac1 and Cdc42. The structure revealed increased substrate tolerance of DOCK7 at the interfaces with switch 1 and residue 56 of Cdc42. Furthermore, molecular dynamics simulations showed a closed-to-open conformational change in the DOCK7 DHR-2 domain between the Cdc42- and Rac1-bound states by lobe B displacement. Our results suggest that lobe B acts as a sensor for identifying different switch 1 conformations and explain how DOCK7 recognizes both Rac1 and Cdc42.