title: Crystallization of Arabidopsis thaliana acetohydroxyacid synthase in complex with the sulfonylurea herbicide chlorimuron ethyl.
abstract: Acetohydroxyacid synthase (AHAS; EC 2.2.1.6) catalyses the formation of 2-acetolactate and 2-aceto-2-hydroxybutyrate as the first step in the biosynthesis of the branched-chain amino acids valine, leucine and isoleucine. The enzyme is inhibited by a wide range of substituted sulfonylureas and imidazolinones and many of these compounds are used as commercial herbicides. Here, the crystallization and preliminary X-ray diffraction analysis of the catalytic subunit of Arabidopsis thaliana AHAS in complex with the sulfonylurea herbicide chlorimuron ethyl are reported. This is the first report of the structure of any plant protein in complex with a commercial herbicide. Crystals diffract to 3.0 A resolution, have unit-cell parameters a = b = 179.92, c = 185.82 A and belong to space group P6(4)22. Preliminary analysis indicates that there is one monomer in the asymmetric unit and that these are arranged as pairs of dimers in the crystal. The dimers form a very open hexagonal lattice, with a high solvent content of 81%.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Molecular and Microbial Sciences, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: S S
authors.initials: SS
authors.lastname: Pang
authors.forename: L W
authors.initials: LW
authors.lastname: Guddat
authors.forename: R G
authors.initials: RG
authors.lastname: Duggleby
mesh_terms: D000095:Acetolactate Synthase / Q000737:chemistry* / Q000235:genetics; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D003460:Crystallization; D018360:Crystallography, X-Ray; D006540:Herbicides / Q000737:chemistry*; D008958:Models, Molecular; D011743:Pyrimidines / Q000737:chemistry*; D011994:Recombinant Proteins; D013453:Sulfonylurea Compounds / Q000737:chemistry*
chemical_list: D006540:Herbicides; D011743:Pyrimidines; D011994:Recombinant Proteins; D013453:Sulfonylurea Compounds; C112343:chlorimuron ethyl; D000095:Acetolactate Synthase