Regulators of the Bacillus subtilis cydABCD operon: identification of a negative regulator, CcpA, and a positive regulator, ResD.
The cydABCD operon of Bacillus subtilis encodes products required for the production of cytochrome bd oxidase. Previous work has shown that one regulatory protein, YdiH (Rex), is involved in the repression of this operon. The work reported here confirms the role of Rex in the negative regulation of the cydABCD operon. Two additional regulatory proteins for the cydABCD operon were identified, namely, ResD, a response regulator involved in the regulation of respiration genes, and CcpA, the carbon catabolite regulator protein. ResD, but not ResE, was required for full expression of the cydA promoter in vivo. ResD binding to the cydA promoter between positions -58 and -107, a region which includes ResD consensus binding sequences, was not enhanced by phosphorylation. A ccpA mutant had increased expression from the full-length cydA promoter during stationary growth compared to the wild-type strain. Maximal expression in a ccpA mutant was observed from a 3'-deleted cydA promoter fusion that lacked the Rex binding region, suggesting that the effect of the two repressors, Rex and CcpA, was cumulative. CcpA binds directly to the cydA promoter, protecting the region from positions -4 to -33, which contains sequences similar to the CcpA consensus binding sequence, the cre box. CcpA binding was enhanced upon addition of glucose-6-phosphate, a putative cofactor for CcpA. Mutation of a conserved residue in the cre box reduced CcpA binding 10-fold in vitro and increased cydA expression in vivo. Thus, CcpA and ResD, along with the previously identified cydA regulator Rex (YdiH), affect the expression of the cydABCD operon. Low-level induction of the cydA promoter was observed in vivo in the absence of its regulatory proteins, Rex, CcpA, and ResD. This complex regulation suggests that the cydA promoter is tightly regulated to allow its expression only at the appropriate time and under the appropriate conditions.
Puri-Taneja
Ankita
A
Laboratory for Molecular Biology, Department of Biological Sciences, University of Illinois at Chicago, 900 S. Ashland Avenue (M/C 567), Chicago, IL 60607, USA.
Schau
Matthew
M
Chen
Yinghua
Y
Hulett
F Marion
FM
D019677:Artificial Gene Fusion; D001412:Bacillus subtilis / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D003580:Cytochromes / Q000096:biosynthesis; D018983:DNA Footprinting; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D024202:Electrophoretic Mobility Shift Assay; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005809:Genes, Regulator; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009876:Operon; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D001616:beta-Galactosidase / Q000096:biosynthesis
D001426:Bacterial Proteins; D003580:Cytochromes; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; C100386:ResD protein, Bacillus subtilis; D014157:Transcription Factors; C069286:catabolite control proteins, bacteria; D001616:beta-Galactosidase