title: CcpA-mediated catabolite activation of the Bacillus subtilis ilv-leu operon and its negation by either CodY- or TnrA-mediated negative regulation.
abstract: The Bacillus subtilis ilv-leu operon functions in the biosynthesis of branched-chain amino acids. It undergoes catabolite activation involving a promoter-proximal cre which is mediated by the complex of CcpA and P-Ser-HPr. This activation of ilv-leu expression is negatively regulated through CodY binding to a high-affinity site in the promoter region under amino acid-rich growth conditions, and it is negatively regulated through TnrA binding to the TnrA box under nitrogen-limited growth conditions. The CcpA-mediated catabolite activation of ilv-leu required a helix face-dependent interaction of the complex of CcpA and P-Ser-HPr with RNA polymerase and needed a 19-nucleotide region upstream of cre for full activation. DNase I footprinting indicated that CodY binding to the high-affinity site competitively prevented the binding of the complex of CcpA and P-Ser-HPr to cre. This CodY binding not only negated catabolite activation but also likely inhibited transcription initiation from the ilv-leu promoter. The footprinting also indicated that TnrA and the complex of CcpA and P-Ser-HPr simultaneously bound to the TnrA box and the cre site, respectively, which are 112 nucleotides apart; TnrA binding to its box was likely to induce DNA bending. This implied that interaction of TnrA bound to its box with the complex of CcpA and P-Ser-HPr bound to cre might negate catabolite activation, but TnrA bound to its box did not inhibit transcription initiation from the ilv-leu promoter. Moreover, this negation of catabolite activation by TnrA required a 26-nucleotide region downstream of the TnrA box.
authors.affiliation: Department of Biotechnology, Faculty of Life Science and Biotechnology, Fukuyama University, Fukuyama-shi, Hiroshima, Japan yfujita@bt.fubt.fukuyama-u.ac.jp.
authors.forename: Yasutaro
authors.initials: Y
authors.lastname: Fujita
authors.affiliation: Department of Biotechnology, Faculty of Life Science and Biotechnology, Fukuyama University, Fukuyama-shi, Hiroshima, Japan.
authors.forename: Takenori
authors.initials: T
authors.lastname: Satomura
authors.affiliation: Department of Biotechnology, Faculty of Life Science and Biotechnology, Fukuyama University, Fukuyama-shi, Hiroshima, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Tojo
authors.affiliation: Department of Biotechnology, Faculty of Life Science and Biotechnology, Fukuyama University, Fukuyama-shi, Hiroshima, Japan.
authors.forename: Kazutake
authors.initials: K
authors.lastname: Hirooka
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018983:DNA Footprinting; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D009584:Nitrogen; D009876:Operon / Q000235:genetics / Q000502:physiology*; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D009584:Nitrogen