title: Effect of mutagenesis at serine 653 of Arabidopsis thaliana acetohydroxyacid synthase on the sensitivity to imidazolinone and sulfonylurea herbicides.
abstract: Resistance to sulfonylurea and imidazolinone herbicides can occur by mutations in acetohydroxyacid synthase (EC 4.1.3.18). Changing serine 653 to asparagine is known to cause insensitivity to imidazolinones but not to sulfonylureas. Here, S-653 of the Arabidopsis thaliana enzyme was mutated to alanine, threonine and phenylalanine. The purified mutated enzymes resemble wild-type in their enzymatic properties. The threonine and phenylalanine mutants are imidazolinone-resistant and the latter is also slightly sulfonylurea-resistant. The alanine mutant remains sensitive to both herbicides. The results suggest that the beta-hydroxyl group is not required for imidazolinone binding and that the size of the side-chain determines resistance.
authors.affiliation: Centre for Protein Structure, Function and Engineering, Department of Biochemistry, University of Queensland, Brisbane, Australia.
authors.forename: Y T
authors.initials: YT
authors.lastname: Lee
authors.forename: A K
authors.initials: AK
authors.lastname: Chang
authors.forename: R G
authors.initials: RG
authors.lastname: Duggleby
mesh_terms: D000095:Acetolactate Synthase / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000201:enzymology*; D001190:Arylsulfonates / Q000494:pharmacology; D006540:Herbicides / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology*; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D009525:Niacin / Q000031:analogs & derivatives / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D015183:Restriction Mapping; D012694:Serine; D013329:Structure-Activity Relationship; D013449:Sulfonamides; D013453:Sulfonylurea Compounds / Q000494:pharmacology*; D014227:Triazines / Q000494:pharmacology
chemical_list: D001190:Arylsulfonates; D006540:Herbicides; D007093:Imidazoles; D011743:Pyrimidines; D011994:Recombinant Proteins; D013449:Sulfonamides; D013453:Sulfonylurea Compounds; D014227:Triazines; C050296:metsulfuron methyl; D009525:Niacin; D012694:Serine; C076656:imazapyr; C112343:chlorimuron ethyl; D000095:Acetolactate Synthase; C037137:chlorsulfuron