Download MendeleyThe GTPase-activating protein p120RasGAP has an evolutionarily conserved "FLVR-unique" SH2 domain.
Jaber Chehayeb, R., Wang, J., Stiegler, A.L., Boggon, T.J.(2020) J Biol Chem 295: 10511-10521
- PubMed: 32540970
- DOI: https://doi.org/10.1074/jbc.RA120.013976
- Primary Citation of Related Structures:
6WAX, 6WAY - PubMed 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 pTyr 1087 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."
Organizational Affiliation:
Yale College, New Haven, Connecticut, USA.
