An octaheme c-type cytochrome from Shewanella oneidensis can reduce nitrite and hydroxylamine.
A c-type cytochrome from Shewanella oneidensis MR-1, containing eight hemes, has been previously designated as an octaheme tetrathionate reductase (OTR). The structure of OTR revealed that the active site contains an unusual lysine-ligated heme, despite the presence of a CXXCH motif in the sequence that would predict histidine ligation. This lysine ligation has been previously observed only in the pentaheme nitrite reductases, suggesting that OTR may have a possible role in nitrite reduction. We have now shown that OTR is an efficient nitrite and hydroxylamine reductase and that ammonium ion is the product. These results indicate that OTR may have a role in the biological nitrogen cycle.
EaStCHEM, School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, UK.
Sally J
SJ
Atkinson
Christopher G
CG
Mowat
Graeme A
GA
Reid
Stephen K
SK
Chapman
D001665:Binding Sites; D002384:Catalysis; D003575:Cytochromes c1 / Q000737:chemistry / Q000378:metabolism*; D006418:Heme / Q000737:chemistry*; D019811:Hydroxylamine / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D020592:Shewanella / Q000201:enzymology*; D013379:Substrate Specificity
D009573:Nitrites; D019811:Hydroxylamine; D006418:Heme; D003575:Cytochromes c1