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Acetohydroxyacid synthase (AHAS; EC 2.2.1.6) is the first enzyme in the biosynthetic pathway of the branched-chain amino acids. It catalyzes the conversion of two molecules of pyruvate into 2-acetolactate or one mole-cule of pyruvate and one molecule of 2-ketobutyrate into 2-aceto-2-hydrox-ybutyrate. | Crystal structures of two novel sulfonylurea herbicides in complex with Arabidopsis thaliana acetohydroxyacid synthase Jian-Guo Wang1 Patrick K.-M. Lee2 Yu-Hui Dong3 Siew Siew Pang2 Ronald G. Duggleby2 f Zheng-Ming Li1 and Luke W. Guddat2 1 State Key Laboratory of Elemento-Organic Chemistry NationalPesticide Engineering Research Center Nankai University Tianjin China 2 Schoolof Molecular and MicrobialSciences The University of Queensland Brisbane Australia 3 Beijing Synchrotron Radiation Facility Institute of High Energy Physics Beijing China Keywords acetohydroxyacid synthase branched-chain amino acids crystal structure herbicide sulfonylurea Correspondence Z.-M. Li State Key Laboratory of Elemento-Organic Chemistry National Pesticide Engineering Research Center Nankai University Tianjin 300071 China Fax 86 22 2350 5948 Tel 86 22 2350 3732 E-mail nkzml@vip.163.com L. W. Guddat Schoolof Molecular and Microbial Sciences The University of Queensland Brisbane Qld 4072 Australia Fax 61 7 3365 4699 Tel 61 7 3365 3549 E-mail luke.guddat@uq.edu.au Present address Department of Biochemistry Monash University Clayton Australia fRDBiotec Little Mountain Australia Database Coordinates and structure factors have been deposited in the Protein Data Bank under the accession numbers 3E9Y and 3EA4 Acetohydroxyacid synthase AHAS EC 2.2.1.6 is the first enzyme in the biosynthetic pathway of the branched-chain amino acids. It catalyzes the conversion of two molecules of pyruvate into 2-acetolactate or one molecule of pyruvate and one molecule of 2-ketobutyrate into 2-aceto-2-hydrox-ybutyrate. AHAS requires the cofactors thiamine diphosphate ThDP Mg2 and FAD for activity. The herbicides that target this enzyme are effective in protecting a broad range of crops from weed species. However resistance in the field is now a serious problem worldwide. To address this two new sulfonylureas monosulfuron and monosulfuron ester have been developed as commercial herbicides in China. These .
