An O2-inducible rubrerythrin-like protein, rubperoxin, is functional as a H2O2 reductase in an obligatory anaerobe Clostridium acetobutylicum

Kawasaki, Shinji; Ono, Masaki; Watamura, Yusuke; Sakai, Yu; Satoh, Takumi; Arai, Toshiaki; Satoh, Junichi; Niimura, Youichi

doi:10.1016/j.febslet.2007.04.050

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Volume 581, Issue 13 , Pages 2460-2464, 29 May 2007

An O₂-inducible rubrerythrin-like protein, rubperoxin, is functional as a H₂O₂ reductase in an obligatory anaerobe Clostridium acetobutylicum

Edited by Richard Cogdell

Department of Biosciences, Tokyo University of Agriculture, Setagaya-ku, Tokyo 156-8502, Japan

Received 23 February 2007; received in revised form 15 April 2007; accepted 16 April 2007. published online 01 May 2007.

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.