Structure of the DOCK2−ELMO1 complex provides insights into regulation of the auto-inhibited state

Abstract

DOCK (dedicator of cytokinesis) proteins are multidomain guanine nucleotide exchange factors (GEFs) for RHO GTPases that regulate intracellular actin dynamics. DOCK proteins share catalytic (DOCK DHR2 ) and membrane-associated (DOCK DHR1 ) domains. The structurally-related DOCK1 and DOCK2 GEFs are specific for RAC, and require ELMO (engulfment and cell motility) proteins for function. The N-terminal RAS-binding domain (RBD) of ELMO (ELMO RBD ) interacts with RHOG to modulate DOCK1/2 activity. Here, we determine the cryo-EM structures of DOCK2−ELMO1 alone, and as a ternary complex with RAC1, together with the crystal structure of a RHOG−ELMO2 RBD complex. The binary DOCK2−ELMO1 complex adopts a closed, auto-inhibited conformation. Relief of auto-inhibition to an active, open state, due to a conformational change of the ELMO1 subunit, exposes binding sites for RAC1 on DOCK2 DHR2 , and RHOG and BAI GPCRs on ELMO1. Our structure explains how up-stream effectors, including DOCK2 and ELMO1 phosphorylation, destabilise the auto-inhibited state to promote an active GEF.

ARF6‐Rac1 signaling‐mediated neurite outgrowth is potentiated by the neuronal adaptor FE65 through orchestrating ARF6 and ELMO1

“…18 Likewise, FE65 binds ELMO1/DOCK1/2 to stimulate ELMO1 by disrupting its autoinhibitory closed conformation 7 and consequently releasing DOCK1/2 from its autoinhibition. 45 The ARF6-FE65-ELMO1/ DOCK1/2 complex is then trafficked through the endosomal recycling pathway to the PM to induce Rac1 activation and consequently neurite outgrowth In conclusion, we demonstrate that FE65 orchestrates ARF6 and ELMO1 to form a tripartite signaling complex and stimulate neurite outgrowth by promoting the PM trafficking of ELMO1 through the ARF6-regulated endosomal recycling pathway ( Figure 6).…”

“…Recently, it has been shown that conformational change of ELMO1 is required for the release of the autoinhibitory conformation of the ELMO1-DOCK bipartite Rac1 GEF complex. 45 Intriguing, an interaction of FE65 and ELMO1 has been shown to promote the relieve of the closed conformation F I G U R E 3 ARF6-FE65-ELMO1 interaction potentiates neurite outgrowth. (A, B, C, D, and E) Rat embryonic E18 cortical neurons were isolated and transfected with EGFP as a cell morphology marker, together with different combinations of plasmid DNAs and/or siRNAs as indicated.…”

“…Recently, it has been shown that conformational change of ELMO1 is required for the release of the autoinhibitory conformation of the ELMO1‐DOCK bipartite Rac1 GEF complex 45 . Intriguing, an interaction of FE65 and ELMO1 has been shown to promote the relieve of the closed conformation of ELMO1 7 .…”

“…FE65 interacts with ARF6 to trigger ARF6 activation 18 . Likewise, FE65 binds ELMO1/DOCK1/2 to stimulate ELMO1 by disrupting its autoinhibitory closed conformation 7 and consequently releasing DOCK1/2 from its autoinhibition 45 . The ARF6‐FE65‐ELMO1/DOCK1/2 complex is then trafficked through the endosomal recycling pathway to the PM to induce Rac1 activation and consequently neurite outgrowth…”

A conserved PI(4,5)P2–binding domain is critical for immune regulatory function of DOCK8

“…GTP-loaded Cdc42 and PI(4,5)P2 serve as the coincidence detection signals for activation of Wiskott-Aldrich syndrome protein, which stimulates Arp2/3 complex–mediated actin polymerization for reorganization of the actin cytoskeleton. In a similar, but distinct way, the DOCK-A subfamily member (e.g., DOCK2), which makes a signaling complex with engulfment and cell motility (ELMO) protein through the SH3 domain ( Hanawa-Suetsugu et al, 2012 ; Chang et al, 2020 ), is recruited to the leading edge of migrating cells through the PI(3,4,5)P3–binding DHR-1 domain in response to chemoattractant signals. The DHR-2 domain of the DOCK-A subfamily activates Rac, which in turn acts in synergy with PI(3,4,5)P3 to activate WAVE complex.…”