RAPISARDA Viviana Andrea
congresos y reuniones científicas
Effectors that modify the expression of NADH dehydrogenase-2 gene: involvement in copper resistance in Escherichia coli
SCHURIG L. A.; VOLENTINI S. I.; RODRÍGUEZ MONTELONGO L.; RAPISARDA V. A.
Congreso; X PABMB Congress, XLI Reunión anual de SAIB y XX Reunión anual SAN; 2005
The respiratory NADH dehydrogenase-2 (NDH-2) of Escherichia coli is a cupric-reductase, coded by ndh gene. In rich medium and MT minimal medium, ndh is expressed only in exponential phase of growth due to the negative regulation of the global transcription factor FNR. However, we observed that in M9 minimal medium, the maximum level of expression was reached in early stationary phase and it was maintained in later stationary phase, even for 48 hs. The determinations were done by using the reporter gene of â-galactosidase under the ndh promoter and also by the NDH-2 activity of a wild-type strain. Based on those data, we cross-checked each differential component in the growth media (M9/ MT) and we determined that phosphate and chloride concentrations define the behavior. The action of these effectors is independent of FNR regulation, as we saw using a fnr- strain. Moreover, the expression in stationary phase enhances the resistance against toxic concentration of copper. In conclusion, the changes in the expression pattern of NDH-2 due to specific components in the culture medium are associated to different copper sensibility, supporting our idea that NDH-2 is involved in the metal homeostasis.