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NADH formation by Na(+)-coupled reversed electron transfer in Klebsiella pneumoniae.
Journal article

NADH formation by Na(+)-coupled reversed electron transfer in Klebsiella pneumoniae.

  • Pfenninger-Li XD Mikrobiologisches Institut, Eidgenössische Technische Hochschule, ETH-Zentrum, Zurich, Switzerland.
  • Dimroth P
  • 1992-07-01
Published in:
  • Molecular microbiology. - 1992
Citrates
Citric Acid
Electron Transport
Electron Transport Complex I
Fermentation
Formates
Klebsiella pneumoniae
NAD
NADH, NADPH Oxidoreductases
Oxidation-Reduction
Sodium
English Citrate is fermented by Klebsiella pneumoniae to 2 acetate, 0.5 formate and 1.2 CO2. The formation of less than 1 formate and greater than 1 CO2 per citrate can be accounted for by the oxidation of formate to CO2 in order to provide reducing equivalents for the assimilation of citrate into cell carbon. A membrane-bound electron transport chain is apparently involved in NADH synthesis by these cells. The electrons from formate oxidation to CO2 are used to reduce ubiquinone to ubiquinol by membrane-bound formate dehydrogenase and ubiquinol further delivers its electrons to NAD+, if this endergonic reaction is powered by delta mu Na+. The endogenous NADH level of K. pneumoniae cells thus increased in the presence of formate in response to a delta pNa+ greater than -100 mV. NADH formation was completely abolished in the presence of oxygen or after addition of hydroxyquinoline-N-oxide, a specific inhibitor of the Na(+)-translocating NADH:ubiquinone oxidoreductase. The increase of endogenous NADH was dependent on the delta pNa+ applied to the cells. Inverted membrane vesicles of K. pneumoniae catalysed the reduction of NAD+ to NADH with formate as electron donor after application of delta mu Na+ of about 120 mV consisting of delta pNa+ of 60 mV and delta psi of the same magnitude. Neither the delta pNa+ nor the delta psi of this size alone was sufficient to drive the endergonic reaction. Strictly anaerobic conditions were required for NADH formation and hydroxyquinoline-N-oxide completely inactivated the reaction.(ABSTRACT TRUNCATED AT 250 WORDS)
Language
  • English
Open access status
closed
Identifiers
Persistent URL
https://sonar.ch/global/documents/190972
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