The alternative oxidase (AOX) gene in Vibrio fischeri is controlled by NsrR and upregulated in response to nitric oxide.
Alternative oxidase (AOX) is a respiratory oxidase found in certain eukaryotes and bacteria; however, its role in bacterial physiology is unclear. Exploiting the genetic tractability of the bacterium Vibrio fischeri, we explore the regulation of aox expression and AOX function. Using quantitative PCR and reporter assays, we demonstrate that aox expression is induced in the presence of nitric oxide (NO), and that the NO-responsive regulatory protein NsrR mediates the response. We have identified key amino acid residues important for NsrR function and experimentally confirmed a bioinformatically predicted NsrR binding site upstream of aox. Microrespirometry demonstrated that oxygen consumption by V. fischeri CydAB quinol oxidase is inhibited by NO treatment, whereas oxygen consumption by AOX is less sensitive to NO. NADH oxidation assays using inverted membrane vesicles confirmed that NO directly inhibits CydAB, and that AOX is resistant to NO inhibition. These results indicate a role for V. fischeri AOX in aerobic respiration during NO stress.
Dunn
Anne K
AK
Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA. akdunn@ou.edu
Karr
Elizabeth A
EA
Wang
Yanling
Y
Batton
Aaron R
AR
Ruby
Edward G
EG
Stabb
Eric V
EV
D048908:Aliivibrio fischeri / Q000201:enzymology* / Q000502:physiology; D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D017930:Genes, Reporter; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000378:metabolism* / Q000633:toxicity; D010088:Oxidoreductases / Q000378:metabolism*; D010101:Oxygen Consumption; D010940:Plant Proteins; D016133:Polymerase Chain Reaction; D020218:Response Elements; D014157:Transcription Factors / Q000378:metabolism*; D000099188:Alternative Oxidase
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D024101:Mitochondrial Proteins; D009569:Nitric Oxide; D010088:Oxidoreductases; D010940:Plant Proteins; D014157:Transcription Factors; D000099188:Alternative Oxidase; C020094:duroquinol oxidase