Structural basis for mutual relief of the Rac guanine nucleotide exchange factor DOCK2 and its partner ELMO1 from their autoinhibited forms

Abstract

DOCK2, a hematopoietic cell-specific, atypical guanine nucleotide exchange factor, controls lymphocyte migration through ras-related C3 botulinum toxin substrate (Rac) activation. Dedicator of cytokinesis 2-engulfment and cell motility protein 1 (DOCK2•ELMO1) complex formation is required for DOCK2-mediated Rac signaling. In this study, we identified the N-terminal 177-residue fragment and the C-terminal 196-residue fragment of human DOCK2 and ELMO1, respectively, as the mutual binding regions, and solved the crystal structure of their complex at 2.1-Å resolution. The C-terminal Prorich tail of ELMO1 winds around the Src-homology 3 domain of DOCK2, and an intermolecular five-helix bundle is formed. Overall, the entire regions of both DOCK2 and ELMO1 assemble to create a rigid structure, which is required for the DOCK2•ELMO1 binding, as revealed by mutagenesis. Intriguingly, the DOCK2•ELMO1 interface hydrophobically buries a residue which, when mutated, reportedly relieves DOCK180 from autoinhibition. We demonstrated that the ELMO-interacting region and the DOCK-homology region 2 guanine nucleotide exchange factor domain of DOCK2 associate with each other for the autoinhibition, and that the assembly with ELMO1 weakens the interaction, relieving DOCK2 from the autoinhibition. The interactions between the N-and C-terminal regions of ELMO1 reportedly cause its autoinhibition, and binding with a DOCK protein relieves the autoinhibition for ras homolog gene family, member G binding and membrane localization. In fact, the DOCK2•-ELMO1 interface also buries the ELMO1 residues required for the autoinhibition within the hydrophobic core of the helix bundle. Therefore, the present complex structure reveals the structural basis by which DOCK2 and ELMO1 mutually relieve their autoinhibition for the activation of Rac1 for lymphocyte chemotaxis.X-ray crystallography | NMR | protein complex | CDM proteins | immunology

Using HHsearch to tackle proteins of unknown function: A pilot study with PH domains

“…Excluding redundant sequences, >200 PH‐like domain structures have been solved. Structures have confirmed earlier identifications made solely on the basis of remote sequence homology in most31, 32 but not all33 cases.…”

ClipR-59 Interacts with Elmo2 and Modulates Myoblast Fusion

“…The question raised is how the same domain mediates the interaction of Elmo2 with both proteins? Studies of the interaction between Elmo and Dock protein revealed that the aPH domain does not directly contact with Dock, but provides a structural determinant in that the helice (␣N and ␣C) before and after the PH domain along the PXXP motif were arranged to direct contact with Dock protein (35,38). In our studies, we found that the aPH domain without these helices was sufficient to interact with ClipR-59 (Fig.…”

“…The Interaction between ClipR-59 and Elmo2 Enhances the Levels of Active Rac1-Elmo2 interacts with the Dock family protein to activate downstream targets including Rac1 (35). To determine whether Elmo2, ClipR-59, and Dock protein forms a tertiary complex, a co-immunoprecipitation assay was carried out with COS-7 cell lysates that express FLAG-Dock180 alone or HA-ClipR-59 plus FLAG-Dock2, or HA-ClipR-59 plus FLAG-Dock180 and Myc-Elmo2, with anti-FLAG antibody.…”

Insights into the biological functions of Dock family guanine nucleotide exchange factors

“…Recent data suggest that Elmo and Dock2 may exist as individual autoinhibited proteins that form a complex following stimulation to relieve both proteins from their inhibited state (Fig. 3A [ii], B; Hanawa-Suetsugu et al 2012). The recruitment of the Elmo/Dock1 complex to the membrane is also guided by Elmo-interacting proteins (Fig.…”