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Structural and functional significance of the highly-conserved residues in Mycobacterium tuberculosis acetohydroxyacid synthase

Paper ID Volume ID Publish Year Pages File Format Full-Text
17205 42651 2014 8 PDF Available
Title
Structural and functional significance of the highly-conserved residues in Mycobacterium tuberculosis acetohydroxyacid synthase
Abstract

•Role of highly conserved His84, Glu85, and Gln86 of M. tuberculosis AHAS was evaluated.•These conserved residues are located in the ThDP binding pocket of AHAS.•Our study validates Glu85 plays a key catalytic function in M. tuberculosis AHAS.•Further, we suggest conserved His84 and Gln86 play a key supporting role in catalysis.

Mycobacterium tuberculosis AHAS is a potential target for the development of novel anti-tuberculosis agents. Silico analysis showed that conserved His84 and Gln86 residues lie in the catalytic dimer interface of M. tuberculosis AHAS. Mutational analyses of these invariants led to significant reduction in their activity with reduced affinity toward the substrate. Importantly, mutation of Gln86 to Trp abolished complete activity. Further, molecular dynamics simulation studies suggested that these residues are likely to play a key role in maintaining the Glu85 side chain in the required geometry with N1′ atom of ThDP during catalysis. In addition, substitution of essential Glu85 by Ala, Asp, and Gln led to severe drop in catalytic activity with reduced affinity toward ThDP confirming its catalytic role in M. tuberculosis AHAS.

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Keywords
M. tuberculosis AHAS, Mycobacterium tuberculosis acetohydroxyacid synthase; CSU, catalytic subunit; ThDP, thiamine diphosphate; BCAA, branched-chain amino acids; MD, molecular dynamicsAcetohydroxyacid synthase; ThDP dependent enzymes; Mutagenesis; Molecul
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Structural and functional significance of the highly-conserved residues in Mycobacterium tuberculosis acetohydroxyacid synthase
Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volumes 58–59, 10 May 2014, Pages 52–59
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering