Crystallographic evidence for substrate-assisted GTP hydrolysis by a small GTP binding protein

Sebastiano Pasqualato, Jacqueline Cherfils

Research output: Contribution to journalArticlepeer-review

Abstract

GTP hydrolysis by small GTP binding proteins of the Ras superfamily is a universal reaction that controls multiple cellular regulations. Its enzymic mechanism has been the subject of long-standing debates as to the existence/identity of the general base and the electronic nature of its transition state. Here we report the high-resolution crystal structure of a small GTP binding protein, Rab11, solved in complex with GDP and Pi. Unexpectedly, a Pi oxygen and the GDP-cleaved oxygen are located less than 2.5 Å apart, suggesting that they share a proton, likely in the form of a low-barrier hydrogen bond. This implies that the γ-phosphate of GTP was protonated; hence, that GTP acts as a general base. Furthermore, this interaction should establish at, and stabilize, the transition state. Altogether, we propose a revised model for the GTPase reaction that should reconcile earlier models into a unique substrate-assisted mechanism.

Original languageEnglish
Pages (from-to)533-540
Number of pages8
JournalStructure
Volume13
Issue number4
DOIs
Publication statusPublished - Apr 2005

ASJC Scopus subject areas

  • Molecular Biology
  • Structural Biology

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