Quaternary structure is an essential component that contributes to the sophisticated allosteric regulation mechanism in a key enzyme from Mycobacterium tuberculosis

Date
2017
Authors
Jiao W
Blackmore NJ
Nazmi AR
Parker EJ
Abstract

The first enzyme of the shikimate pathway, 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAH7PS), adopts a range of distinct allosteric regulation mechanisms in different organisms, related to different quaternary assemblies. DAH7PS from Mycobacterium tuberculosis (MtuDAH7PS) is a homotetramer, with the allosteric sites in close proximity to the interfaces. Here we examine the importance of the quaternary structure on catalysis and regulation, by amino acid substitution targeting the tetramer interface of MtuDAH7PS. Using only single amino acid substitutions either in, or remote from the interface, two dimeric variants of MtuDAH7PS (MtuDAH7PS F227D and MtuDAH7PS G232P ) were successfully generated. Both dimeric variants maintained activity due to the distance between the sites of amino acid substitution and the active sites, but attenuated catalytic efficiency was observed. Both dimeric variants showed significantly disrupted allosteric regulation with greatly impaired binding affinity for one of the allosteric ligands. Molecular dynamics simulations revealed changes in protein dynamics and average conformations in the dimeric variant caused by amino acid substitution remote to the tetramer interface (MtuDAH7PS G232P ), which are consistent with the observed reduction in catalytic efficiency and loss of allosteric response.

Description
Citation
Jiao W, Blackmore NJ, Nazmi AR, Parker EJ (2017). Quaternary structure is an essential component that contributes to the sophisticated allosteric regulation mechanism in a key enzyme from Mycobacterium tuberculosis. PLoS ONE. 12(6). e0180052-.
Keywords
Ngā upoko tukutuku/Māori subject headings
ANZSRC fields of research
Fields of Research::31 - Biological sciences::3101 - Biochemistry and cell biology::310106 - Enzymes
Field of Research::03 - Chemical Sciences::0304 - Medicinal and Biomolecular Chemistry
Rights
This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.