Overlapping role of the outer membrane cytochromes of Shewanella oneidensis MR-1 in the reduction of manganese(IV) oxide
Article first published online: 13 JUN 2003
Letters in Applied Microbiology
Volume 37, Issue 1, pages 21–25, July 2003
How to Cite
Myers, J.M. and Myers, C.R. (2003), Overlapping role of the outer membrane cytochromes of Shewanella oneidensis MR-1 in the reduction of manganese(IV) oxide. Letters in Applied Microbiology, 37: 21–25. doi: 10.1046/j.1472-765X.2003.01338.x
- Issue published online: 13 JUN 2003
- Article first published online: 13 JUN 2003
- 2002/363: received 25 November 2002, revised 21 February 2003 and accepted 4 March 2003
- outer membrane;
- Shewanella oneidensis
Aim: To determine if the outer membrane (OM) cytochromes OmcA and OmcB of the metal-reducing bacterium Shewanella oneidensis MR-1 have distinct or overlapping roles in the reduction of insoluble manganese(IV) oxide.
Methods and Results: The gene replacement mutant (OMCA1) which lacks OmcA was partially deficient in Mn(IV) reduction. Complementation of OMCA1 with a vector (pVK21) that contains omcB but not omcA restored Mn(IV) reduction to levels that were even greater than those of wild-type. Examination of the OM of OMCA1/pVK21 revealed greater than wild-type levels of OmcB protein and specific haem content.
Conclusions: Overexpression of OmcB can compensate for the absence of OmcA in the reduction of insoluble Mn(IV) oxides. Therefore, there is at least a partial overlap in the roles of these OM cytochromes in the reduction of insoluble Mn(IV) oxide.
Significance: The overlapping roles of these two cytochromes has important implications for understanding the mechanism by which MR-1 reduces insoluble metal oxides. There is no obligatory sequential electron transfer from one cytochrome to the other. They could both potentially serve as terminal reductases for extracellular electron acceptors.