Inhibition of Thymidine Transport in dnaA Mutants of Escherichia coli

摘要: DnaA protein is the initiator of chromosomal DNA replication in Escherichia coli. We report here our evidence that thymidine transport across cytoplasmic membranes temperature-sensitive dnaA mutants greatly decreased at a permissive temperature for growth mutants. Complementation analysis with plasmid containing wild type gene and P1 phage-mediated transduction confirmed mutations thednaA were responsible phenotype. A low level nucleoside mutant was specific thymidine; activities other nucleosides much same as those cells. Membrane vesicles prepared from showed activity did No significant difference kinase, which known to facilitate transport, seen between An increase pool dTTP, negative regulator observed mutant. Based on these observations, we suggest inhibition caused by increases dTTP pool.