An Allele of gyrA Prevents Salmonella enterica Serovar Typhimurium from Using Succinate as a Carbon Source

A mutant gyrA allele resulting in an A271E substitution in the DNA gyrase protein generated a strain unable to grow on the C 4 -dicarboxylates succinate, malate, and fumarate. Bacteria harboring gyrA751 displayed decreased negative supercoiling in cells. Expression of the dctA gene, which encodes the C 4 -dicarboxylate transporter, was reduced in a gyrA751 mutant, providing the first evidence that dctA expression is supercoiling sensitive and uncovering a simple metabolic screen for lesions in gyrase that reduce negative supercoiling.