Motility at high temperature is inhibited due to the repression of flagellar synthesis. A mutation, named tim, that suppreses nonmotile phenotype at high temperature has been isolated by an insertion of Tn10-LacZ fusion hopper. The fusion was localized at 49.5 min. on E. coli linkage map and the fused gene was identified as ackA, which is the structural gene of Acetate kinase. Tim shows The following phenotypes: reduced growth rate in complete media, enhanced chemotactic ability, increased tumbling frequency in free swimming condition, and higher expression of Trg trancducer gene at normal and high temperature than that of wild type. Pta, phosphotransacetylase gene, mutation shows the same phenotypes comparing with tim and other ackA mutant strains. These phenotypes caused by blocking the pathway of acetyl-CoA to acetate might be due to the depletion or accumulation of acetate metabolite and that affects to the level of CheY acetylation.
