Evidence for the role of soluble cytochrome c in the dissimilatory reduction of nitrite and nitrous oxide by cells of Paracoccus denitrificans.
The role of periplasmic cytochrome c in the denitrification pathway has been investigated using a wild-type and/or a cytochrome c deficient strain of Paracoccus denitrificans. The reconstitution experiments with the isolated proteins showed that bacterial cytochrome c-550 restored the electron transport from the cytoplasmic membrane to soluble nitrite reductase (cytochrome cd1). In response to decreased aeration lasting 3 h, the HUUG25 strain synthesized nitrous-oxide reductase significantly starved of electrons from the respiratory chain and only very small amounts of soluble cytochrome c. The membrane-bound part of the respiratory chain catalyzing the reduction of soluble cytochrome c resembled an autologous region in wild-type cells kinetically and by its sensitivity to antimycin. In the periplasmic fraction obtained from anaerobically grown wild-type cells N2O caused the reoxidation of endogenous cytochrome(s) c previously reduced by N,N,N',N' tetramethyl-p-phenylenediamine plus ascorbate. All these results indicate the involvement of soluble cytochrome(s) c as the electron donor(s) for the reduction of NO2- and N2O in the periplasmic space of cells.
Matchová
I
I
Masaryk University, Department of Biochemistry, Brno, Czechoslovakia.
Kucera
I
I
D003574:Cytochrome c Group / Q000502:physiology*; D004579:Electron Transport; D005798:Genes, Bacterial; D007700:Kinetics; D009154:Mutation; D009573:Nitrites / Q000378:metabolism*; D009609:Nitrous Oxide / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010231:Paracoccus denitrificans / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D013057:Spectrum Analysis
D003574:Cytochrome c Group; D009573:Nitrites; D009609:Nitrous Oxide; D010100:Oxygen