Pyruvate formate-lyase is not essential for nitrate respiration by Escherichia coli.
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 catabolize pyruvate in nitrate-respiring cells. The activities of PFL and PDH measured after growth with nitrate are commensurate with this proposal.
Kaiser
M
M
Lehrstuhl für Mikrobiologie, Universität München, FRG.
Sawers
G
G
D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D000332:Aerobiosis; D000693:Anaerobiosis; D004252:DNA Mutational Analysis; D004579:Electron Transport; D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism*; D017353:Gene Deletion; D007655:Ketoglutarate Dehydrogenase Complex / Q000032:analysis; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000032:analysis; D009566:Nitrates / Q000378:metabolism*; D010084:Oxidation-Reduction; D011768:Pyruvate Dehydrogenase Complex / Q000235:genetics / Q000378:metabolism*; D013385:Succinate Dehydrogenase / Q000032:analysis
D009566:Nitrates; D011768:Pyruvate Dehydrogenase Complex; D007655:Ketoglutarate Dehydrogenase Complex; D013385:Succinate Dehydrogenase; D009565:Nitrate Reductases; D050901:Nitrate Reductase; D000123:Acetyltransferases; C022560:formate C-acetyltransferase