Work

19F NMR and DFT Analysis Reveal Structural and Electronic Transition State Features for RhoA‐Catalyzed GTP Hydrolysis

Year: 2016

Type: article

Abstract: Molecular details for RhoA/GAP catalysis of the hydrolysis of GTP to GDP are poorly understood. We use 19F NMR chemical shifts in the MgF3− transition state analogue (TSA) complex as a spectroscopic reporter to indicate electron distribution for the γ‐PO3− oxygens in the corresponding TS, implying that oxygen coordinated to Mg has the greatest electron density. This was validated by QM calculations giving a picture of the electronic properties of the transition state (TS) for nucleophilic attack of water on the γ‐PO3− group based on the structure of a RhoA/GAP‐GDP‐MgF3− TSA complex. The TS model displays a network of 20 hydrogen bonds, including the GAP Arg85′ side chain, but neither phosphate torsional strain nor general base catalysis is evident. The nucleophilic water occupies a reactive location different from that in multiple ground state complexes, arising from reorientation of the Gln‐63 carboxamide by Arg85′ to preclude direct hydrogen bonding from water to the target γ‐PO3− group.

Source: Angewandte Chemie

DOI: 10.1002/ange.201509477

Authors: Yi Jin, Robert W. Molt, Jonathan P. Waltho, Nigel G. J. Richards, G. Michael Blackburn

Institutions: University of Sheffield, Indiana University – Purdue University Indianapolis, University of Manchester, Cardiff University

Language: English

Topic: Chemical Reaction Mechanisms

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $5,790

Funders: Indiana University-Purdue University Indianapolis, Biotechnology and Biological Sciences Research Council