title: A critical phosphate concentration in the stationary phase maintains ndh gene expression and aerobic respiratory chain activity in Escherichia coli.
abstract: 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 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 37 mM 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/NAD+ 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.
authors.affiliation: Departamento Bioquímica de la Nutrición, Instituto Superior de Investigaciones Biológicas (Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de Tucumán), San Miguel de Tucumán, Argentina.
authors.forename: Lici A
authors.initials: LA
authors.lastname: Schurig-Briccio
authors.forename: María R
authors.initials: MR
authors.lastname: Rintoul
authors.forename: Sabrina I
authors.initials: SI
authors.lastname: Volentini
authors.forename: Ricardo N
authors.initials: RN
authors.lastname: Farías
authors.forename: Laura
authors.initials: L
authors.lastname: Baldomà
authors.forename: Josefa
authors.initials: J
authors.lastname: Badía
authors.forename: Luisa
authors.initials: L
authors.lastname: Rodríguez-Montelongo
authors.forename: Viviana A
authors.initials: VA
authors.lastname: Rapisarda
mesh_terms: D000332:Aerobiosis; D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000378:metabolism; D004579:Electron Transport; D004926:Escherichia coli / Q000737:chemistry / Q000502:physiology*; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D050296:Microbial Viability; D009243:NAD / Q000378:metabolism; D009245:NADH Dehydrogenase / Q000096:biosynthesis*; D010100:Oxygen / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D011725:Pyridines / Q000032:analysis; D012808:Sigma Factor / Q000378:metabolism; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D010710:Phosphates; D011725:Pyridines; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D009243:NAD; C088908:NADH dehydrogenase II; D009245:NADH Dehydrogenase; D001616:beta-Galactosidase; D010100:Oxygen