title: Pathway for H2O2 and O2 detoxification in Clostridium acetobutylicum.
abstract: An unusual non-haem diiron protein, reverse rubrerythrin (revRbr), is known to be massively upregulated in response to oxidative stress in the strictly anaerobic bacterium Clostridium acetobutylicum. In the present study both in vivo and in vitro results demonstrate an H2O2 and O2 detoxification pathway in C. acetobutylicum involving revRbr, rubredoxin (Rd) and NADH : rubredoxin oxidoreductase (NROR). RevRbr exhibited both NADH peroxidase (NADH : H2O2 oxidoreductase) and NADH oxidase (NADH : O2 oxidoreductase) activities in in vitro assays using NROR as the electron-transfer intermediary from NADH to revRbr. Rd increased the NADH consumption rate by serving as an intermediary electron-transfer shuttle between NROR and revRbr. While H2O2 was found to be the preferred substrate for revRbr, its relative oxidase activity was found to be significantly higher than that reported for other Rbrs. A revRbr-overexpressing strain of C. acetobutylicum showed significantly increased tolerance to H2O2 and O2 exposure. RevRbr thus appears to protect C. acetobutylicum against oxidative stress by functioning as the terminal component of an NADH peroxidase and NADH oxidase.
authors.affiliation: Division of Microbiology, Institute of Biological Sciences, University of Rostock, Albert-Einstein-Str. 3, D-18051 Rostock, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Riebe
authors.affiliation: Division of Microbiology, Institute of Biological Sciences, University of Rostock, Albert-Einstein-Str. 3, D-18051 Rostock, Germany.
authors.forename: Ralf-Jörg
authors.initials: RJ
authors.lastname: Fischer
authors.affiliation: Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Wampler
authors.affiliation: Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, USA.
authors.forename: Donald M
authors.initials: DM
authors.lastname: Kurtz
authors.affiliation: Division of Microbiology, Institute of Biological Sciences, University of Rostock, Albert-Einstein-Str. 3, D-18051 Rostock, Germany.
authors.forename: Hubert
authors.initials: H
authors.lastname: Bahl
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D046969:Clostridium acetobutylicum / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D006422:Hemerythrin / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism*; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism; D012416:Rubredoxins / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D006422:Hemerythrin; D009097:Multienzyme Complexes; D012416:Rubredoxins; C055857:rubrerythrins; D006861:Hydrogen Peroxide; D010544:Peroxidases; C021845:NAD+ peroxidase; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D010100:Oxygen