Discovery of Novel Acetohydroxyacid Synthase Inhibitors as Active Agents against Mycobacterium tuberculosis by Virtual Screening and Bioassay

Acetohydroxyacid synthase (AHAS) has been regarded as a promising drug target against Mycobacterium tuberculosis (MTB) as it catalyzes the biosynthesis of branched-chain amino acids. In this study, 23 novel AHAS inhibitors were identified through molecular docking followed by similarity search. The determined IC(50) values range from 0.385 ± 0.026 μM to >200 μM against bacterium AHAS. Five of the identified compounds show significant in vitro activity against H37Rv strains (MICs in the range of 2.5-80 mg/L) and clinical MTB strains, including MDR and XDR isolates. More impressively, compounds 5 and 7 can enhance the killing ability against macrophages infected pathogen remarkably. This study suggests our discovered inhibitors can be further developed as novel anti-MTB therapeutics targeting AHAS.

[1]  L. Sacks,et al.  Developing new drugs for the treatment of drug-resistant tuberculosis: a regulatory perspective. , 2008, Tuberculosis.

[2]  P. Kollman,et al.  A Second Generation Force Field for the Simulation of Proteins, Nucleic Acids, and Organic Molecules , 1995 .

[3]  Guang-Fu Yang,et al.  QSAR and 3D-QSAR analysis of structurally diverse ALS inhibitors: sulfonylureas and triazolopyrimidine-2-sulfonamides , 1999 .

[4]  Guang-Fu Yang,et al.  Syntheses and herbicidal activity of new triazolopyrimidine-2-sulfonamides as acetohydroxyacid synthase inhibitor. , 2010, Bioorganic & medicinal chemistry.

[5]  Moon-Young Yoon,et al.  Characterization of acetohydroxyacid synthase from Mycobacterium tuberculosis and the identification of its new inhibitor from the screening of a chemical library , 2005, FEBS letters.

[6]  R S Chaleff,et al.  Acetolactate Synthase Is the Site of Action of Two Sulfonylurea Herbicides in Higher Plants , 1984, Science.

[7]  Manfred J. Sippl,et al.  Thirty years of environmental health research--and growing. , 1996, Nucleic Acids Res..

[8]  Ying Xiong,et al.  Computational determination of fundamental pathway and activation barriers for acetohydroxyacid synthase‐catalyzed condensation reactions of α‐keto acids , 2009, J. Comput. Chem..

[9]  J. Schloss,et al.  Inhibitors of branched-chain amino acid biosynthesis as potential antituberculosis agents. , 1998, The Journal of antimicrobial chemotherapy.

[10]  Gang Wang,et al.  Synthesis and evaluation of novel monosubstituted sulfonylurea derivatives as antituberculosis agents. , 2012, European journal of medicinal chemistry.

[11]  Li Zhang,et al.  Rational Design Based on Bioactive Conformation Analysis of Pyrimidinylbenzoates as Acetohydroxyacid Synthase Inhibitors by Integrating Molecular Docking, CoMFA, CoMSIA, and DFT Calculations , 2007, J. Chem. Inf. Model..

[12]  Guang-Fu Yang,et al.  Design and syntheses of novel phthalazin-1(2H)-one derivatives as acetohydroxyacid synthase inhibitors. , 2006, Journal of agricultural and food chemistry.

[13]  Z. Barak,et al.  Biosynthesis of 2-aceto-2-hydroxy acids: acetolactate synthases and acetohydroxyacid synthases. , 1998, Biochimica et biophysica acta.

[14]  Zhen Xi,et al.  Development of a general quantum‐chemical descriptor for steric effects: Density functional theory based QSAR study of herbicidal sulfonylurea analogues , 2006, J. Comput. Chem..

[15]  Guang-Fu Yang,et al.  Design and synthesis of N-2,6-difluorophenyl-5-methoxyl-1,2,4-triazolo[1,5-a]-pyrimidine-2-sulfonamide as acetohydroxyacid synthase inhibitor. , 2009, Bioorganic & medicinal chemistry.

[16]  Dong-Wan Koo,et al.  In vitro and ex vivo activity of new derivatives of acetohydroxyacid synthase inhibitors against Mycobacterium tuberculosis and non-tuberculous mycobacteria. , 2008, International journal of antimicrobial agents.

[17]  J M Thornton,et al.  LIGPLOT: a program to generate schematic diagrams of protein-ligand interactions. , 1995, Protein engineering.

[18]  C. Hill,et al.  Mutagenesis of Escherichia coli acetohydroxyacid synthase isoenzyme II and characterization of three herbicide-insensitive forms. , 1998, The Biochemical journal.

[19]  J. Thornton,et al.  PROCHECK: a program to check the stereochemical quality of protein structures , 1993 .

[20]  Eric Arnoult,et al.  The challenge of new drug discovery for tuberculosis , 2011, Nature.

[21]  Jufang He,et al.  Prevalence of multidrug and extensively drug-resistant tuberculosis in Beijing, China: a hospital-based retrospective study. , 2010, Japanese journal of infectious diseases.

[22]  J. Irwin,et al.  Benchmarking sets for molecular docking. , 2006, Journal of medicinal chemistry.

[23]  Guang-Fu Yang,et al.  Computational Design and Discovery of Conformationally Flexible Inhibitors of Acetohydroxyacid Synthase to Overcome Drug Resistance Associated with the W586L Mutation , 2008, ChemMedChem.

[24]  Luke W. Guddat,et al.  Molecular Basis of Sulfonylurea Herbicide Inhibition of Acetohydroxyacid Synthase* , 2003, The Journal of Biological Chemistry.

[25]  J. McCourt,et al.  Acetohydroxyacid synthase and its role in the biosynthetic pathway for branched-chain amino acids , 2006, Amino Acids.

[26]  R. Larossa,et al.  The sulfonylurea herbicide sulfometuron methyl is an extremely potent and selective inhibitor of acetolactate synthase in Salmonella typhimurium. , 1984, The Journal of biological chemistry.

[27]  W. Kabsch.  A discussion of the solution for the best rotation to relate two sets of vectors , 1978 .

[28]  V. Subbulakshmi,et al.  Inactivation of the ilvB1 gene in Mycobacterium tuberculosis leads to branched-chain amino acid auxotrophy and attenuation of virulence in mice. , 2009, Microbiology.

[29]  Z. Barak,et al.  Acetohydroxyacid synthase from Mycobacterium avium and its inhibition by sulfonylureas and imidazolinones. , 2003, Biochimica et biophysica acta.

[30]  Ning Ma,et al.  Structure-activity relationships for a new family of sulfonylurea herbicides , 2005, J. Comput. Aided Mol. Des..

[31]  D. Shaner,et al.  Imidazolinones: potent inhibitors of acetohydroxyacid synthase. , 1984, Plant physiology.

[32]  Daniela Josa,et al.  Molecular modelling of Mycobacterium tuberculosis acetolactate synthase catalytic subunit and its molecular docking study with inhibitors , 2008 .

[33]  Ronald G. Duggleby,et al.  Mutagenesis studies on the sensitivity of Escherichia coli acetohydroxyacid synthase II to herbicides and valine. , 2000 .

[34]  Vinayak Singh,et al.  Biochemical and transcription analysis of acetohydroxyacid synthase isoforms in Mycobacterium tuberculosis identifies these enzymes as potential targets for drug development. , 2011, Microbiology.

[35]  J. Thompson,et al.  CLUSTAL W: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. , 1994, Nucleic acids research.