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

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 homotetram...

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Bibliographic Details
Published in:PloS one 2017-06, Vol.12 (6), p.e0180052-e0180052
Main Authors: Jiao, Wanting, Blackmore, Nicola J, Nazmi, Ali Reza, Parker, Emily J
Format: Article
Language:English
Subjects:
3-Deoxy-7-Phosphoheptulonate Synthase - chemistry
3-Deoxy-7-Phosphoheptulonate Synthase - genetics
3-Deoxy-7-Phosphoheptulonate Synthase - metabolism
Affinity
Allosteric properties
Allosteric Regulation
Amino Acid Substitution
Amino acids
Analysis
Assemblies
Attenuation
Binding sites
Biochemistry
Biology and Life Sciences
Biosynthesis
Catalysis
Crystallography, X-Ray
Dimerization
Enzymes
Genetic aspects
Interfaces
Kinases
Ligands
Molecular dynamics
Molecular Dynamics Simulation
Molecular structure
Mutagenesis
Mycobacterium tuberculosis - enzymology
Phenylalanine - metabolism
Phosphate
Phosphates
Physical Sciences
Protein structure
Protein Structure, Quaternary
Proteins
Proximity
Quaternary structure
Regulation
Sedimentation & deposition
Tryptophan - metabolism
Tuberculosis
Wilkins, Maurice
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Summary: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 (MtuDAH7PSF227D and MtuDAH7PSG232P) 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 (MtuDAH7PSG232P), which are consistent with the observed reduction in catalytic efficiency and loss of allosteric response.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0180052