title: Five-gene cluster in Clostridium thermoaceticum consisting of two divergent operons encoding rubredoxin oxidoreductase- rubredoxin and rubrerythrin-type A flavoprotein- high-molecular-weight rubredoxin.
abstract: A five-gene cluster encoding four nonheme iron proteins and a flavoprotein from the thermophilic anaerobic bacterium Clostridium thermoaceticum (Moorella thermoacetica) was cloned and sequenced. Based on analysis of deduced amino acid sequences, the genes were identified as rub (rubredoxin), rbo (rubredoxin oxidoreductase), rbr (rubrerythrin), fprA (type A flavoprotein), and a gene referred to as hrb (high-molecular-weight rubredoxin). Northern blot analysis demonstrated that the five-gene cluster is organized as two subclusters, consisting of two divergently transcribed operons, rbr-fprA-hrb and rbo-rub. The rbr, fprA, and rub genes were expressed in Escherichia coli, and their encoded recombinant proteins were purified. The molecular masses, UV-visible absorption spectra, and cofactor contents of the recombinant rubrerythrin, rubredoxin, and type A flavoprotein were similar to those of respective homologs from other microorganisms. Antibodies raised against Desulfovibrio vulgaris Rbr reacted with both native and recombinant Rbr from C. thermoaceticum, indicating that this protein was expressed in the native organism. Since Rbr and Rbo have been recently implicated in oxidative stress protection in several anaerobic bacteria and archaea, we suggest a similar function of these proteins in oxygen tolerance of C. thermoaceticum.
authors.affiliation: Center for Biological Resource Recovery and Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-7229, USA.
authors.forename: A
authors.initials: A
authors.lastname: Das
authors.forename: E D
authors.initials: ED
authors.lastname: Coulter
authors.forename: D M
authors.initials: DM
authors.lastname: Kurtz
authors.forename: L G
authors.initials: LG
authors.lastname: Ljungdahl
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D003001:Cloning, Molecular; D003013:Clostridium / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005288:Ferredoxins / Q000235:genetics* / Q000378:metabolism; D005420:Flavoproteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D006422:Hemerythrin; D008969:Molecular Sequence Data; D005810:Multigene Family; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D009876:Operon; D018384:Oxidative Stress / Q000235:genetics; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012416:Rubredoxins / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D005288:Ferredoxins; D005420:Flavoproteins; D006422:Hemerythrin; D011994:Recombinant Proteins; D012416:Rubredoxins; C055857:rubrerythrins; C023091:rubredoxin-NAD+ reductase; D009247:NADH, NADPH Oxidoreductases