The GTPase-activating protein p120RasGAP has an evolutionarily conserved "FLVR-unique" SH2 domain

J Biol Chem. 2020 Jul 31;295(31):10511-10521. doi: 10.1074/jbc.RA120.013976. Epub 2020 Jun 15.

Abstract

The Src homology 2 (SH2) domain has a highly conserved architecture that recognizes linear phosphotyrosine motifs and is present in a wide range of signaling pathways across different evolutionary taxa. A hallmark of SH2 domains is the arginine residue in the conserved FLVR motif that forms a direct salt bridge with bound phosphotyrosine. Here, we solve the X-ray crystal structures of the C-terminal SH2 domain of p120RasGAP (RASA1) in its apo and peptide-bound form. We find that the arginine residue in the FLVR motif does not directly contact pTyr1087 of a bound phosphopeptide derived from p190RhoGAP; rather, it makes an intramolecular salt bridge to an aspartic acid. Unexpectedly, coordination of phosphotyrosine is achieved by a modified binding pocket that appears early in evolution. Using isothermal titration calorimetry, we find that substitution of the FLVR arginine R377A does not cause a significant loss of phosphopeptide binding, but rather a tandem substitution of R398A (SH2 position βD4) and K400A (SH2 position βD6) is required to disrupt the binding. These results indicate a hitherto unrecognized diversity in SH2 domain interactions with phosphotyrosine and classify the C-terminal SH2 domain of p120RasGAP as "FLVR-unique."

Keywords: FLVR motif; GTPase-activating protein (GAP); RASA1; RasGAP; Src homology 2 domain (SH2 domain); X-ray crystallography; p120RasGAP; phosphotyrosine; protein structure; protein–protein interaction.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Crystallography, X-Ray
  • Evolution, Molecular*
  • Humans
  • p120 GTPase Activating Protein / chemistry*
  • p120 GTPase Activating Protein / genetics
  • p120 GTPase Activating Protein / metabolism
  • src Homology Domains

Substances

  • RASA1 protein, human
  • p120 GTPase Activating Protein

Associated data

  • PDB/6PXC
  • PDB/1SPS
  • PDB/5TQ1
  • PDB/2CIA
  • PDB/2PXC
  • PDB/4U1P
  • PDB/2GSB
  • PDB/1D4T