Skip to content
Licensed Unlicensed Requires Authentication Published by De Gruyter August 19, 2008

Fluoride complexes of oncogenic Ras mutants to study the Ras-RasGAP interaction

  • Lothar Gremer , Bernd Gilsbach , Mohammad Reza Ahmadian and Alfred Wittinghofer
From the journal Biological Chemistry

Abstract

Down-regulation of Ras signalling is mediated by specific GTPase-activating proteins (GAPs), which stimulate the very slow GTPase reaction of Ras by 105-fold. The basic features of the GAP activity involve the stabilisation of both switch regions of Ras in the transition state, and the insertion of an arginine finger. In the case of oncogenic Ras mutations, the features of the active site are disturbed. To understand these features in more detail, we investigated the effects of oncogenic mutations of Ras and compared the GAP-stimulated GTPase reaction with the ability to form GAP-mediated aluminium or beryllium fluoride complexes. In general, we found a correlation between the size of the amino acid at position 12, the GTPase activity and ability to form aluminium fluoride complexes. While Gly12 is very sensitive to even the smallest possible structural change, Gly13 is much less sensitive to steric hindrance, but is sensitive to charge. Oncogenic mutants of Ras defective in the GTPase activity can however form ground-state GppNHp complexes with GAP, which can be mimicked by beryllium fluoride binding. We show that beryllium fluoride complexes are less sensitive to structural changes and report on a state close to but different from the ground state of the GAP-stimulated GTPase reaction.


Corresponding author

Received: 2007-12-23
Accepted: 2008-4-1
Published Online: 2008-08-19
Published in Print: 2008-09-01

©2008 by Walter de Gruyter Berlin New York

Downloaded on 29.3.2024 from https://www.degruyter.com/document/doi/10.1515/BC.2008.132/html
Scroll to top button