Osmotic repression of anaerobic metabolic systems in Escherichia coli.
The influence of the osmolarity of the growth medium on anaerobic fermentation and nitrate respiratory pathways was analyzed. The levels of several enzymes, including formate dehydrogenase, hydrogenase, and nitrate reductase, plus a nickel uptake system were examined, as was the expression of the corresponding structural and regulatory genes. While some functions appear to be only moderately affected by an increase in osmolarity, others were found to vary considerably. An increase in the osmolarity of the medium inhibits both fermentation and anaerobic respiratory pathways, though in a more dramatic fashion for the former. fnr expression is affected by osmolarity, but the repression of anaerobic gene expression was shown to be independent of FNR regulatory protein, at least for hyd-17 and fdhF. This repression could be mediated by the intracellular concentration of potassium and is reversed by glycine betaine.
Gouesbet
G
G
Département Membranes et Osmorégulation, Université de Rennes I, France.
Abaibou
H
H
Wu
L F
LF
Mandrand-Berthelot
M A
MA
Blanco
C
C
D000693:Anaerobiosis / Q000502:physiology; D001692:Biological Transport; D002455:Cell Division / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology*; D005285:Fermentation / Q000502:physiology; D005560:Formate Dehydrogenases / Q000032:analysis; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000187:drug effects; D005809:Genes, Regulator / Q000187:drug effects; D006864:Hydrogenase / Q000032:analysis; D009532:Nickel / Q000378:metabolism; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000032:analysis; D009566:Nitrates / Q000378:metabolism; D009994:Osmolar Concentration; D010101:Oxygen Consumption / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D014882:Water-Electrolyte Balance / Q000502:physiology*
D009566:Nitrates; D012965:Sodium Chloride; D009532:Nickel; D006864:Hydrogenase; D005560:Formate Dehydrogenases; D009565:Nitrate Reductases; D050901:Nitrate Reductase; D011188:Potassium