Rhodobactor sphaeroides haem protein: a novel cytochrome with nitric oxide dioxygenase activity

L Bor-Ran, JLR Anderson, CG Mowat, CS Miles, GA Reid, SK Chapman

Research output: Contribution to journalArticle (Academic Journal)peer-review

3 Citations (Scopus)

Abstract

Rhodobacter sphaeroides produces a novel cytochrome, designated as SHP (sphaeroides haem protein), that is unusual in having asparagine as a redox-labile haem ligand. The gene encoding SHP is contained within an operon that also encodes a DHC (dihaem cytochrome c) and a membrane-associated cytochrome b. DHC and SHP have been shown to have high affinity for each other at low ionic strength (Kd =0.2 μM), and DHC is able to reduce SHP very rapidly. The reduced form of the protein, SHP2+ (reduced or ferrous SHP), has high affinity for both oxygen and nitric oxide (NO). It has been shown that the oxyferrous form, SHPsup>2+–O2 (oxygen-bound form of SHP), reacts rapidly with NO to produce nitrate, whereas SHPsup>2+–NO (the NO-bound form of SHP) will react with superoxide with the same product formed. It is therefore possible that SHP functions physiologically as a nitric oxide dioxygenase, protecting the organism against NO poisoning, and we propose a possible mechanism for this process.
Translated title of the contributionRhodobactor sphaeroides haem protein: a novel cytochrome with nitric oxide dioxygenase activity
Original languageEnglish
Pages (from-to)992 - 995
Number of pages4
JournalBiochemical Society Transactions
Volume36 (5)
DOIs
Publication statusPublished - Oct 2008

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