title: Expanded roles of leucine-responsive regulatory protein in transcription regulation of theEscherichia coligenome: Genomic SELEX screening of the regulation targets.
abstract: Leucine-responsive regulatory protein (Lrp) is a transcriptional regulator for the genes involved in transport, biosynthesis and catabolism of amino acids inEscherichia coli. In order to identify the whole set of genes under the direct control of Lrp, we performed Genomic SELEX screening and identified a total of 314 Lrp-binding sites on theE. coligenome. As a result, the regulation target of Lrp was predicted to expand from the hitherto identified genes for amino acid metabolism to a set of novel target genes for utilization of amino acids for protein synthesis, including tRNAs, aminoacyl-tRNA synthases and rRNAs. Northern blot analysis indicated alteration of mRNA levels for at least some novel targets, including the aminoacyl-tRNA synthetase genes. Phenotype MicroArray of thelrpmutant indicated significant alteration in utilization of amino acids and peptides, whilst metabolome analysis showed variations in the concentration of amino acids in thelrpmutant. From these two datasets we realized a reverse correlation between amino acid levels and cell growth rate: fast-growing cells contain low-level amino acids, whilst a high level of amino acids exists in slow-growing cells. Taken together, we propose that Lrp is a global regulator of transcription of a large number of the genes involved in not only amino acid transport and metabolism, but also amino acid utilization.
authors.affiliation: Research Center for Micro-Nano Technology, Hosei University, Koganei, Tokyo, Japan.|Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, Japan.|Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta, Yokohama, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Shimada
authors.affiliation: Institute for Advanced Biosciences, Keio University, Yamagata, Japan.|Department of Chemistry and Material Engineering, Tsuruoka National College of Technology, Yamagata, Japan.
authors.forename: Natsumi
authors.initials: N
authors.lastname: Saito
authors.affiliation: School of Agriculture, Meiji University, Kawasaki, Kanagawa, Japan.
authors.forename: Michihisa
authors.initials: M
authors.lastname: Maeda
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta, Yokohama, Japan.
authors.forename: Kan
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Research Center for Micro-Nano Technology, Hosei University, Koganei, Tokyo, Japan.|Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Ishihama
keywords: Escherichia coli genome; Genomic SELEX; leucine response regulator; regulation target; transcription factor