PMID:22349433

Citation	Rycovska, A, Hatahet, L, Fendler, K and Michel, H (2012) The nitrite transport protein NirC from Salmonella typhimurium is a nitrite/proton antiporter. Biochim. Biophys. Acta 1818:1342-50
Abstract	In anaerobically grown bacteria, transport of nitrite is catalyzed by an integral membrane protein of the form ate-nitrite transporter family, NirC, which in Salmonella typhimurium plays a critical role in intracellular virulence. We present a functional characterization of the S. typhimurium nitrite transporter StmNirC in native membrane vesicles as well as purified and reconstituted into proteoliposomes. Using an electrophysiological technique based on solid supported membranes, we show nitrite induced translocation of negative charges into proteoliposomes reconstituted with purified StmNirC. These data demonstrate the electrogenicity of StmNirC and its substrate specificity for nitrite. Monitoring changes in ΔpH on everted membrane vesicles containing overexpressed StmNirC using acridine orange as a pH indicator we demonstrate that StmNirC acts as a secondary active transporter. It promotes low affinity transport of nitrite coupled to H(+) antiport with a pH independent profile in the pH range from 6 to 8. In addition to nitrite also nitrate is transported by StmNirC, but with reduced flux and complete absence of proton antiport activity. Taken together, these data suggest a bispecific anion selectivity of StmNirC with an ion specific transport mode. This may play a role in regulating nitrite transport under physiological conditions.
Links	PubMed Online version:10.1016/j.bbamem.2012.02.004
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOHS:A8A5H4	Contributes to	GO:0005215 : transporter activity	IDA: Inferred from Direct Assay:	F	in figure 3 and 4 assay shows tranporter activity due to NirC	complete

References

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