Elaborate transcription regulation of the Bacillus subtilis ilv-leu operon involved in the biosynthesis of branched-chain amino acids through global regulators of CcpA, CodY and TnrA.
The Bacillus subtilis ilv-leu operon involved in the biosynthesis of branched-chain amino acids is under negative regulation mediated by TnrA and CodY, which recognize and bind to their respective cis-elements located upstream of the ilv-leu promoter. This operon is known to be under CcpA-dependent positive regulation. We have currently identified a catabolite-responsive element (cre) for this positive regulation (bases -96 to -82; +1 is the ilv-leu transcription initiation base) by means of DNase I-footprinting in vitro, and deletion and base-substitution analyses of cre. Under nitrogen-rich growth conditions in glucose-minimal medium supplemented with glutamine and amino acids, CcpA and CodY exerted positive and negative regulation of ilv-leu, respectively, but TnrA did not function. Moreover, CcpA and CodY were able to function without their counteracting regulation of each other, although the CcpA-dependent positive regulation did not overcome the CodY-dependent negative regulation. Furthermore, under nitrogen-limited conditions in glucose-minimal medium with glutamate as the sole nitrogen source, CcpA and TnrA exerted positive and negative regulation, respectively, but CodY did not function. This CcpA-dependent positive regulation occurred without the TnrA-dependent negative regulation. However, the TnrA-dependent negative regulation did not occur without the CcpA-dependent positive regulation, raising the possibility that this negative regulation might decrease the CcpA-dependent positive regulation. The physiological role of this elaborate transcription regulation of the B. subtilis ilv-leu operon in overall metabolic regulation in this organism is discussed.
Tojo
Shigeo
S
Department of Biotechnology, Faculty of Life Science and Biotechnology, Fukuyama University, 985 Sanzo, Higashimura-cho, Fukuyama-shi, Hiroshima 729-0292, Japan.
Satomura
Takenori
T
Morisaki
Kaori
K
Deutscher
Josef
J
Hirooka
Kazutake
K
Fujita
Yasutaro
Y
D000597:Amino Acids, Branched-Chain / Q000096:biosynthesis*; D001412:Bacillus subtilis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D007532:Isoleucine / Q000096:biosynthesis; D007930:Leucine / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D009876:Operon; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014633:Valine / Q000096:biosynthesis
D000597:Amino Acids, Branched-Chain; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; C101458:ScgR protein, Bacillus subtilis; D014157:Transcription Factors; C069286:catabolite control proteins, bacteria; D007532:Isoleucine; D007930:Leucine; D014633:Valine; D009584:Nitrogen