RAPISARDA Viviana Andrea
A critical phosphate concentration in stationary phase maintains ndh gene expression and aerobic respiratory chain activity in Escherichia coli
SCHURIG-BRICCIO, L. A.; RINTOUL, M. R.; VOLENTINI S. I.; FARÍAS, R. N.; BALDOMA, L.; BADIA, J.; RODRÍGUEZ-MONTELONGO, L.; RAPISARDA, V. A.
FEMS MICROBIOLOGY LETTERS
Blackwell Publishing Ltd.
Año: 2008 vol. 284 p. 76 - 83
Escherichia coli 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 exponential growth phase and repressed in stationary phase. We report the maintenance of NDH-2 activity and ndh expression in late stationary phase when cells were grown in media containing at least 37 mM phosphate. Gene regulation was independent of RpoS and other transcription factors described to interact with ndh promoter. At this critical phosphate concentration, cell viability, oxygen consumption rate and NADH/NAD+ ratio were maintained in stationary phase. These physiological parameters gradually changed, but NDH-2 activity remained high for up 94 h. Phosphate seems to trigger an internal signal in stationary phase mediated by systems not yet described.