3o5c

Publication Abstract from PubMed

Bacterial diheme c-type cytochrome peroxidases (BCCPs) catalyze the periplasmic reduction of hydrogen peroxide to water. The gamma-proteobacterium S. oneidensis produces the peroxidase CcpA under a number of anaerobic conditions including dissimilatory iron reducing conditions. We wanted to understand the function of this protein in the organism as well as its putative connection to the electron transport chain to ferric iron. CcpA was isolated and tested for its peroxidase activity as well as for its structural conformation as analyzed by X-ray crystallography. CcpA exhibited in vitro peroxidase activity and had a structure typical for diheme peroxidases. It was produced in almost equal amounts under anaerobic as well as microaerophilic conditions. With 50 mM ferric citrate and 50 muM oxygen in the growth medium, CcpA expression results in a strong selective advantage for the cell as was detected in competitive growth experiments between wild type and DeltaccpA mutant cells that lack the entire ccpA gene due to a markerless deletion. We were unable to reduce CcpA directly with CymA, MtrA or FccA which are known key players of the electron transport chain to ferric iron and fumarate but identified the small monoheme ScyA as an electron transport mediator between CymA and BCCP. To our knowledge this is the first detailed description of a complete electron transport chain to a periplasmic c-type cytochrome peroxidase. The study furthermore reports the possibility to establish a specific electron transport chain using c-type cytochromes.

Investigation of the electron transport chain to and the catalytic activity of the diheme cytochrome c peroxidase CcpA of Shewanella oneidensis.,Schutz B, Seidel J, Sturm G, Einsle O, Gescher J Appl Environ Microbiol. 2011 Jul 8. PMID:21742904^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.