Characterization of an operon encoding two c-type cytochromes, an aa(3)-type cytochrome oxidase, and rusticyanin in Thiobacillus ferrooxidans ATCC 33020.
Despite the importance of Thiobacillus ferrooxidans in bioremediation and bioleaching, little is known about the genes encoding electron transfer proteins implicated in its energetic metabolism. This paper reports the sequences of the four cox genes encoding the subunits of an aa(3)-type cytochrome c oxidase. These genes are in a locus containing four other genes: cyc2, which encodes a high-molecular-weight cytochrome c; cyc1, which encodes a c(4)-type cytochrome (c(552)); open reading frame 1, which encodes a putative periplasmic protein of unknown function; and rus, which encodes rusticyanin. The results of Northern and reverse transcription-PCR analyses indicated that these eight genes are cotranscribed. Two transcriptional start sites were identified for this operon. Upstream from each of the start sites was a sigma70-type promoter recognized in Escherichia coli. While transcription in sulfur-grown T. ferrooxidans cells was detected from the two promoters, transcription in ferrous-iron-grown T. ferrooxidans cells was detected only from the downstream promoter. The cotranscription of seven genes encoding redox proteins suggests that all these proteins are involved in the same electron transfer chain; a model taking into account the biochemistry and the genetic data is discussed.
Appia-Ayme
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C
Laboratoire de Chimie Bactérienne, Institut de Biologie Structurale et de Microbiologie, Centre National de la Recherche Scientifique, 13402 Marseille Cedex 20, France.
Guiliani
N
N
Ratouchniak
J
J
Bonnefoy
V
V
D001400:Azurin / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics; D003574:Cytochrome c Group / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics* / Q000378:metabolism; D005798:Genes, Bacterial; D046911:Macromolecular Substances; D016366:Open Reading Frames; D009876:Operon; D015183:Restriction Mapping; D013855:Thiobacillus / Q000235:genetics* / Q000378:metabolism
D001426:Bacterial Proteins; D003574:Cytochrome c Group; D046911:Macromolecular Substances; C083951:cytochrome c553; C012543:rusticyanin; D001400:Azurin; C022302:cytochrome C-552; D003576:Electron Transport Complex IV