A critical phosphate concentration in the stationary phase maintains

LICI A. SCHURIG-BRICCIO; MARIA R. RINTOUL; SABRINA I. VOLENTINI; RICARDO N. FARIAS; LAURA BALDOMA`; JOSEFA BADIA; LUISA RODRIGUEZ-MONTELONGO; VIVIANA A. RAPISARDA

FEMS MICROBIOLOGY LETTERS

Blackwell Publishing

Lugar: England; Año: 2008 vol. 284 p. 76 - 83

0378-1097

Escherichia coli NADH dehydrogenase-2 (NDH-2) is a primary dehydrogenase in aerobic respiration that shows cupric-reductase activity. The enzyme is encoded by aerobic respiration that shows cupric-reductase activity. The enzyme is encoded by NADH dehydrogenase-2 (NDH-2) is a primary dehydrogenase in aerobic respiration that shows cupric-reductase activity. The enzyme is encoded by ndh, which is highly regulated by global transcription factors. It was described that the gene is expressed in the exponential growth phase and repressed in late stationary phase. We report the maintenance of NDH-2 activity and ndh expression in the stationary phase when cells were grown in media containing at least 37mM phosphate. Gene regulation was independent of RpoS and other transcription factors described to interact with the ndh promoter. At this critical phosphate concentration, cell viability, oxygen consumption rate, and NADH/NAD1 ratio were maintained in the stationary phase. These physiological parameters gradually changed, but NDH-2 activity remained high for up to 94 h. Phosphate seems to trigger an internal signal in the stationary phase mediated by systems not yet described.