%0 Journal Article %A Larossa, Robert A. %A Van Dyk, Tina K. %T Leaky Pantothenate and Thiamin Mutations of Salmonella typhimurium Conferring Sulphometuron Methyl Sensitivity %D 1989 %J Microbiology, %V 135 %N 8 %P 2209-2222 %@ 1465-2080 %R https://doi.org/10.1099/00221287-135-8-2209 %I Microbiology Society, %X The herbicide suphometuron methyl inhibits the utilization of pyruvate and 2-ketobutyrate by the branched-chain amino acid biosynthetic enzyme acetolactate synthase. Eighteen insertions of the transposon Tn10 into the genome of Salmonella typhimurium LT2 caused hypersensitivity to this herbicide. Five of these insertions conferred a partial auxotrophic requirement. Concurrent herbicide sensitivity and heat-labile pantothenate auxotrophy was due to panD::Tn10 mutations, while coincident sulphometuron methyl sensitivity and thiamin auxotrophy was attributable to thiA::Tn10 mutations. The phenotypes of these mutations suggested that coenzyme A and thiamin pyrophosphate availability modulated the cells’ response to sulphometuron methyl. A model suggesting a key role for 2-ketobutyrate accumulation in herbicide action is supported by the function of thiamin pyrophosphate in 2-ketoacid metabolism and the known role of a 2-ketoacid in coenzyme A synthesis. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-135-8-2209