title: Characterization of acetohydroxyacid synthase from Mycobacterium tuberculosis and the identification of its new inhibitor from the screening of a chemical library.
abstract: Acetohydroxyacid synthase (AHAS) is a thiamin diphosphate- (ThDP-) and FAD-dependent enzyme that catalyzes the first common step in the biosynthetic pathway of the branched-amino acids such as leucine, isoleucine, and valine. The genes of AHAS from Mycobacterium tuberculosis were cloned, and overexpressed in E. coli and purified to homogeneity. The purified AHAS from M. tuberculosis is effectively inhibited by pyrazosulfuron ethyl (PSE), an inhibitor of plant AHAS enzyme, with the IC(50) (inhibitory concentration 50%) of 0.87 microM. The kinetic parameters of M. tuberculosis AHAS were determined, and an enzyme activity assay system using 96-well microplate was designed. After screening of a chemical library composed of 5600 compounds using the assay system, a new class of AHAS inhibitor was identified with the IC(50) in the range of 1.8-2.6 microM. One of the identified compounds (KHG20612) further showed growth inhibition activity against various strains of M. tuberculosis. The correlation of the inhibitory activity of the identified compound against AHAS to the cell growth inhibition activity suggested that AHAS might be served as a target protein for the development of novel anti-tuberculosis therapeutics.
authors.affiliation: Department of Chemistry, Hanyang University, Seoul 133-791, Korea.
authors.forename: Kyoung-Jae
authors.initials: KJ
authors.lastname: Choi
authors.forename: Yeon Gyu
authors.initials: YG
authors.lastname: Yu
authors.forename: Hoh Gyu
authors.initials: HG
authors.lastname: Hahn
authors.forename: Jung-Do
authors.initials: JD
authors.lastname: Choi
authors.forename: Moon-Young
authors.initials: MY
authors.lastname: Yoon
mesh_terms: D000095:Acetolactate Synthase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism; D000995:Antitubercular Agents / Q000378:metabolism; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001681:Biological Assay; D015195:Drug Design; D006540:Herbicides / Q000737:chemistry / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000235:genetics; D011720:Pyrazoles / Q000378:metabolism; D011743:Pyrimidines / Q000378:metabolism
chemical_list: D000596:Amino Acids; D000995:Antitubercular Agents; D001426:Bacterial Proteins; D006540:Herbicides; D011720:Pyrazoles; D011743:Pyrimidines; C433343:ethyl 5-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-1-methylpyrazole-4-carboxylate; D000095:Acetolactate Synthase