title: Coordinated patterns of cytochrome bd and lactate dehydrogenase expression in Bacillus subtilis.
abstract: A variety of pathways for electron and carbon flow in the soil bacterium Bacillus subtilis are differentially expressed depending on whether oxygen is present in the cell environment. This study characterizes the regulation of the respiratory oxidase cytochrome bd and the NADH-linked fermentative lactate dehydrogenase (LDH). Transcription of the cydABCD operon, encoding cytochrome bd, is highly regulated and only becomes activated at low oxygen availability. This induction is not dependent on the gene encoding the redox regulator Fnr or the genes encoding the ResDE two-component regulatory system. The DNA-binding protein YdiH was found to be a principal regulator that controls cydABCD expression. Transcription from the cyd promoter is stimulated 15-fold by a region located upstream of the core promoter. The upstream region may constitute a binding site for an unidentified transcription activator that is likely to influence the level of transcription but not its timing, which is negatively controlled by YdiH. This report provides evidence that YdiH also functions as a repressor of the ldh gene encoding LDH and of a gene, ywcJ, which encodes a putative formate-nitrite transporter. Based on the similarity between YdiH and the Rex protein of Streptomyces coelicolor, it is proposed that YdiH serves as a redox sensor, the activity of which is regulated by cellular differences in the free levels of NAD+ and NADH. It is suggested that ydiH be renamed as rex.
authors.affiliation: Department of Cell and Organism Biology, Lund University, Sölvegatan 35, SE-223 62 Lund, Sweden.
authors.forename: Jonas T
authors.initials: JT
authors.lastname: Larsson
authors.affiliation: Department of Cell and Organism Biology, Lund University, Sölvegatan 35, SE-223 62 Lund, Sweden.
authors.forename: Annika
authors.initials: A
authors.lastname: Rogstam
authors.affiliation: Department of Cell and Organism Biology, Lund University, Sölvegatan 35, SE-223 62 Lund, Sweden.
authors.forename: Claes
authors.initials: C
authors.lastname: von Wachenfeldt
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003580:Cytochromes / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D007770:L-Lactate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D009243:NAD / Q000378:metabolism* / Q000494:pharmacology; D020411:Oligonucleotide Array Sequence Analysis; D009876:Operon; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology; D010101:Oxygen Consumption; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D003580:Cytochromes; D004268:DNA-Binding Proteins; D009243:NAD; D010088:Oxidoreductases; D007770:L-Lactate Dehydrogenase; D010100:Oxygen