An evolutionarily conserved autoinhibitory molecular switch in ELMO proteins regulates Rac signaling

Curr Biol. 2010 Nov 23;20(22):2021-7. doi: 10.1016/j.cub.2010.10.028. Epub 2010 Oct 28.

Abstract

Dedicator of cytokinesis (DOCK) proteins are guanine nucleotide exchange factors (GEFs) controlling the activity of Rac1/Cdc42 during migration, phagocytosis, and myoblast fusion [1-4]. Engulfment and cell motility (ELMO) proteins bind a subset of DOCK members and are emerging as critical regulators of Rac signaling [5-10]. Although formation of a DOCK180/ELMO complex is not essential for Rac1 activation, ELMO mutants deficient in binding to DOCK180 are unable to promote cytoskeleton remodeling [11]. How ELMO regulates signaling through DOCK GEFs is poorly understood. Here, we identify an autoinhibitory switch in ELMO presenting homology to a regulatory unit described for Dia formins. One part of the switch, composed of a Ras-binding domain (RBD) and Armadillo repeats, is positioned N-terminally while the other is housed in the C terminus. We demonstrate interaction between these fragments, suggesting autoinhibition of ELMO. Using a bioluminescence resonance energy transfer biosensor, we establish that ELMO undergoes conformational changes upon disruption of autoinhibition. We found that engagement of ELMO to RhoG, or with DOCK180, promotes the relief of autoinhibition in ELMO. Functionally, we found that ELMO mutants with impaired autoregulatory activity promote cell elongation. These results demonstrate an unsuspected level of regulation for Rac1 signaling via autoinhibition of ELMO.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / chemistry*
  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / physiology
  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Biosensing Techniques
  • Computational Biology
  • Conserved Sequence
  • Drosophila / genetics
  • Drosophila / metabolism
  • Drosophila Proteins / chemistry
  • HEK293 Cells
  • Humans
  • Models, Biological
  • Molecular Sequence Data
  • Protein Structure, Tertiary
  • Signal Transduction*
  • Two-Hybrid System Techniques
  • rac GTP-Binding Proteins / chemistry
  • rac GTP-Binding Proteins / metabolism
  • rac1 GTP-Binding Protein / genetics
  • rac1 GTP-Binding Protein / metabolism*
  • rac1 GTP-Binding Protein / physiology

Substances

  • Adaptor Proteins, Signal Transducing
  • Ced-12 protein, Drosophila
  • DOCK1 protein, human
  • Drosophila Proteins
  • ELMO1 protein, human
  • rac GTP-Binding Proteins
  • rac1 GTP-Binding Protein