PMID:17241202

Citation	Pittman, MS, Elvers, KT, Lee, L, Jones, MA, Poole, RK, Park, SF and Kelly, DJ (2007) Growth of Campylobacter jejuni on nitrate and nitrite: electron transport to NapA and NrfA via NrfH and distinct roles for NrfA and the globin Cgb in protection against nitrosative stress. Mol. Microbiol. 63:575-90
Abstract	Pathways of electron transport to periplasmic nitrate (NapA) and nitrite (NrfA) reductases have been investigated in Campylobacter jejuni, a microaerophilic food-borne pathogen. The nap operon is unusual in lacking napC (encoding a tetra-haem c-type cytochrome) and napF, but contains a novel gene of unknown function, napL. The iron-sulphur protein NapG has a major role in electron transfer to the NapAB complex, but we show that slow nitrate-dependent growth of a napG mutant can be sustained by electron transfer from NrfH, the electron donor to the nitrite reductase NrfA. A napL mutant possessed approximately 50% lower NapA activity than the wild type but showed normal growth with nitrate as the electron acceptor. NrfA was constitutive and was shown to play a role in protection against nitrosative stress in addition to the previously identified NO-inducible single domain globin, Cgb. However, nitrite also induced cgb expression in an NssR-dependent manner, suggesting that growth of C. jejuni with nitrite causes nitrosative stress. This was confirmed by lack of growth of cgb and nssR mutants, and slow growth of the nrfA mutant, in media containing nitrite. Thus, NrfA and Cgb together provide C. jejuni with constitutive and inducible components of a robust defence against nitrosative stress.
Links	PubMed Online version:10.1111/j.1365-2958.2006.05532.x
Keywords	Adaptation, Physiological; Animals; Anti-Bacterial Agents/pharmacology; Artificial Gene Fusion; Bacterial Proteins; Blotting, Western; Campylobacter jejuni/drug effects; Campylobacter jejuni/growth & development; Campylobacter jejuni/metabolism; Chickens; Electron Transport; Gene Deletion; Gene Expression Regulation, Bacterial; Hemoglobins/biosynthesis; Hemoglobins/genetics; Hemoglobins/physiology; Microbial Sensitivity Tests; Microbial Viability; Models, Biological; Multigene Family; Mutagenesis, Insertional; Nitrates/metabolism; Nitric Oxide Donors/pharmacology; Nitrites/metabolism; Oxidoreductases/genetics; Oxidoreductases/physiology; Truncated Hemoglobins; beta-Galactosidase/analysis; beta-Galactosidase/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
CAMJE:Q0P8Q2		GO:0009061: anaerobic respiration	ECO:0000315:		P		Figure 3a Wild Type stain of C. jejuni with nrfA gene shows growth under limited oxygen with nitrite, while mutant strain (without nfrA) shows no growth	complete CACAO 9554
CAMJE:Q0P8Q2		GO:0016966 : cellular detoxification of nitrogen compound	ECO:0000315:		P		Figure 5. Shows the nrfA mutant when compared with the WT strain detoxifies NO under aerobic and anerobic conditions.	complete CACAO 9559
CAMJE:Q0P8Q2		GO:0042597: periplasmic space	ECO:0000314:		C		Mutagenesis of nrfA in C. jejuni resulted in the complete absence of NrfA protein in periplasmic extracts, as evidenced by immunoblotting with cross-reactive anti-E. coli NrfA antibodies (data not shown)	complete CACAO 9606
CAMJE:Q0P8Q2	involved_in	GO:0009061: anaerobic respiration	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
CAMJE:Q0P8Q2	enables	GO:0016966: nitric oxide reductase activity	ECO:0000315: mutant phenotype evidence used in manual assertion		F		Seeded From UniProt	complete
CAMJE:Q0P8Q2	part_of	GO:0042597: periplasmic space	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete

References

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