A flavo-diiron protein from Desulfovibrio vulgaris with oxidase and nitric oxide reductase activities. Evidence for an in vivo nitric oxide scavenging function.
A few members of a widespread class of bacterial and archaeal flavo-diiron proteins, dubbed FprAs, have been shown to function as either oxidases (dioxygen reductases) or scavenging nitric oxide reductases, but the questions of which of these functions dominates in vivo for a given FprA and whether all FprAs function as oxidases or nitric oxide reductases remain to be clarified. To address these questions, an FprA has been characterized from the anaerobic sulfate-reducing bacterium Desulfovibrio vulgaris. The gene encoding this D. vulgaris FprA lies downstream of an operon encoding superoxide reductase and rubredoxin, consistent with an O(2)-scavenging oxidase function for this FprA. The recombinant D. vulgaris FprA can indeed serve as the terminal component of an NADH oxidase. However, this oxidase turnover results in irreversible inactivation of the enzyme. On the other hand, the recombinant D. vulgaris FprA shows robust anaerobic nitric oxide reductase activity in vitro and also protects a nitric oxide-sensitive Escherichia coli strain against exposure to exogenous nitric oxide. It is, therefore, proposed that this D. vulgaris FprA functions as a scavenging nitric oxide reductase in vivo and that this activity protects D. vulgaris against anaerobic exposure to nitric oxide. The location of a gene encoding a second FprA homologue in the D. vulgaris genome also suggests its involvement in nitrogen oxide metabolism.
Silaghi-Dumitrescu
Radu
R
Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, Georgia 30602, USA.
Ng
Kim Yong
KY
Viswanathan
Rathinam
R
Kurtz
Donald M
DM
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D016969:Desulfovibrio vulgaris / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology / Q000254:growth & development; D005420:Flavoproteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D016166:Free Radical Scavengers / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification
D001426:Bacterial Proteins; D005420:Flavoproteins; D016166:Free Radical Scavengers; D011994:Recombinant Proteins; D009569:Nitric Oxide; D007501:Iron; D010088:Oxidoreductases; C034747:nitric-oxide reductase