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Pyruvate formate-lyase is not essential for nitrate respiration by Escherichia coli

M. Kaiser, G. Sawers
DOI: http://dx.doi.org/10.1111/j.1574-6968.1994.tb06759.x 163-168 First published online: 1 April 1994


Defined deletion mutants of Escherichia coli defective for the synthesis of pyruvate formate-lyase (PFL) or pyruvate dehydrogenase (PDH) were analysed in regards their growth in batch culture and their enzyme levels under fermentative and nitrate respiratory conditions. A pfl mutant proved not to be completely auxotrophic for acetate when grown anaerobically in glucose minimal medium. In contrast, a pfl aceEF double mutant exhibited an absolute requirement for acetate, indicating that PDH is the source of acetyl-CoA in the pfl mutant. Growth of both pfl and aceEF single mutants under nitrate respiratory conditions was essentially indistinguishable from the wild-type. Thus, either PFL or PDH can be used to catabolise pyruvate in nitrate-respiring cells. The activities of PFL and PDH measured after growth with nitrate are commensurate with this proposal.

Key words
  • Pyruvate formate-lyase
  • Pyruvate dehydrogenase
  • Anaerobiosis
  • Nitrate respiration
  • Escherichia coli

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