title: An O2-inducible rubrerythrin-like protein, rubperoxin, is functional as a H2O2 reductase in an obligatory anaerobe Clostridium acetobutylicum.
abstract: Clostridium acetobutylicum, an obligatory anaerobe, is able to grow microoxically with the accumulation of two functionally unknown O2-induced proteins identified by two-dimensional electrophoresis. One was determined to be a novel type rubrerythrin-like protein, named rubperoxin (Rpr) in this study, that conserves one rubredoxin-type Fe(SCys)(4) site per polypeptide in the N-terminus. Recombinant rubperoxin expressed in E. coli purified in its oxidized form is a dimer with optical absorption maxima at 492, 377, and 277nm. Reduced rubperoxin is rapidly and fully oxidized by a half molar ratio of H2O2 per mole protein, and slowly oxidized by t-butyl hydroperoxide and O2. Cell-free extracts from microoxically grown cells efficiently reduce rubperoxin when NAD(P)H is used as the electron donor (preferentially reduced by NADH). These results strongly suggest that rubperoxin is involved in NAD(P)H-dependent H2O2 detoxification in vivo.
authors.affiliation: Department of Biosciences, Tokyo University of Agriculture, Setagaya-ku, Tokyo 156-8502, Japan. kawashin@nodai.ac.jp
authors.forename: Shinji
authors.initials: S
authors.lastname: Kawasaki
authors.forename: Masaki
authors.initials: M
authors.lastname: Ono
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Watamura
authors.forename: Yu
authors.initials: Y
authors.lastname: Sakai
authors.forename: Takumi
authors.initials: T
authors.lastname: Satoh
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Arai
authors.forename: Junichi
authors.initials: J
authors.lastname: Satoh
authors.forename: Youichi
authors.initials: Y
authors.lastname: Niimura
mesh_terms: D000332:Aerobiosis; D000595:Amino Acid Sequence; D000693:Anaerobiosis; D001421:Bacteria, Anaerobic / Q000201:enzymology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D046969:Clostridium acetobutylicum / Q000201:enzymology*; D017124:Conserved Sequence; D004790:Enzyme Induction; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D006861:Hydrogen Peroxide / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D010544:Peroxidases / Q000235:genetics* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D006861:Hydrogen Peroxide; D010544:Peroxidases