Open AccessEnzymatic Removal of Nitric Oxide Catalyzed by Cytochrome c ′ in Rhodobacter capsulatus
Author(s) -
Rebecca Cross,
David Lloyd,
Robert K. Poole,
James Moir
Publication year - 2001
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.183.10.3050-3054.2001
Subject(s) - rhodobacter , cytochrome , cytochrome c oxidase , biology , cytochrome p450 reductase , biochemistry , cytochrome c peroxidase , cytochrome c , reductase , denitrification , denitrifying bacteria , oxidase test , coenzyme q – cytochrome c reductase , enzyme , chemistry , organic chemistry , nitrogen , gene , mutant , mitochondrion
Cytochrome c' from Rhodobacter capsulatus has been shown to confer resistance to nitric oxide (NO). In this study, we demonstrated that the amount of cytochrome c' synthesized for buffering of NO is insufficient to account for the resistance to NO but that the cytochrome-dependent resistance mechanism involves the catalytic breakdown of NO, under aerobic and anaerobic conditions. Even under aerobic conditions, the NO removal is independent of molecular oxygen, suggesting cytochrome c' is a NO reductase. Indeed, we have measured the product of NO breakdown to be nitrous oxide (N(2)O), thus showing that cytochrome c' is behaving as a NO reductase. The increased resistance to NO conferred by cytochrome c' is distinct from the NO reductase pathway that is involved in denitrification. Cytochrome c' is not required for denitrification, but it has a role in the removal of externally supplied NO. Cytochrome c' synthesis occurs aerobically and anaerobically but is partly repressed under denitrifying growth conditions when other NO removal systems are operative. The inhibition of respiratory oxidase activity of R. capsulatus by NO suggests that one role for cytochrome c' is to maintain oxidase activity when both NO and O(2) are present.