title: Molecular basis of sulfonylurea herbicide inhibition of acetohydroxyacid synthase.
abstract: Acetohydroxyacid synthase (AHAS) (acetolactate synthase, EC ) catalyzes the first step in branched-chain amino acid biosynthesis and is the target for sulfonylurea and imidazolinone herbicides. These compounds are potent and selective inhibitors, but their binding site on AHAS has not been elucidated. Here we report the 2.8 A resolution crystal structure of yeast AHAS in complex with a sulfonylurea herbicide, chlorimuron ethyl. The inhibitor, which has a K(i) of 3.3 nm, blocks access to the active site and contacts multiple residues where mutation results in herbicide resistance. The structure provides a starting point for the rational design of further herbicidal compounds.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Siew Siew
authors.initials: SS
authors.lastname: Pang
authors.forename: Luke W
authors.initials: LW
authors.lastname: Guddat
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Duggleby
mesh_terms: D000095:Acetolactate Synthase / Q000494:pharmacology*; D001665:Binding Sites; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D005656:Fungal Proteins / Q000378:metabolism; D006540:Herbicides / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011743:Pyrimidines / Q000494:pharmacology; D013453:Sulfonylurea Compounds / Q000494:pharmacology*
chemical_list: D005656:Fungal Proteins; D006540:Herbicides; D007093:Imidazoles; D011743:Pyrimidines; D013453:Sulfonylurea Compounds; C112343:chlorimuron ethyl; D000095:Acetolactate Synthase