title: Structural and functional significance of the highly-conserved residues in Mycobacterium tuberculosis acetohydroxyacid synthase.
abstract: 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.
authors.affiliation: Department of Chemistry, Institute of Natural Science, Hanyang University, Seoul 133791, Republic of Korea. Electronic address: irshad@hanyang.ac.kr.
authors.forename: Irshad Ahmed
authors.initials: IA
authors.lastname: Baig
authors.affiliation: Department of Chemistry, Institute of Natural Science, Hanyang University, Seoul 133791, Republic of Korea. Electronic address: answl84@naver.com.
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Moon
authors.affiliation: Department of Chemistry, Institute of Natural Science, Hanyang University, Seoul 133791, Republic of Korea. Electronic address: minseo2527@hanmail.net.
authors.forename: Min-Seo
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Department of Agricultural Biotechnology, National Academy of Agricultural Science, Suwon 441707, Republic of Korea. Electronic address: bskoo@rda.go.kr.
authors.forename: Bon-Sung
authors.initials: BS
authors.lastname: Koo
authors.affiliation: Department of Chemistry, Institute of Natural Science, Hanyang University, Seoul 133791, Republic of Korea. Electronic address: myyoon@hanyang.ac.kr.
authors.forename: Moon-Young
authors.initials: MY
authors.lastname: Yoon
mesh_terms: D000095:Acetolactate Synthase / Q000737:chemistry*; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D002384:Catalysis; D017124:Conserved Sequence; D019281:Dimerization; D004926:Escherichia coli / Q000378:metabolism; D018698:Glutamic Acid / Q000737:chemistry; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013835:Thiamine Pyrophosphate / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D018698:Glutamic Acid; D000095:Acetolactate Synthase; D013835:Thiamine Pyrophosphate
keywords: Acetohydroxyacid synthase; Molecular dynamics; Molecular modeling; Mutagenesis; ThDP dependent enzymes