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Catabolite Repression and Pyruvate Metabolism in Escherichia coli¹

^a Department of Microbiology, North Carolina State University, Raleigh, North Carolina 27607

ABSTRACT

A study was made of the reactions involved in the cellular regulatory function known as catabolite repression. These studies employed the glucose-repressible, ß-galactosidase system of Escherichia coli and involved an investigation of glucose dissimilation under cultural conditions capable of permitting or preventing expression of catabolite repression. The results indicated that reactions associated with pyruvate decarboxylation are of particular importance in influencing repression. This conclusion was based on results obtained by measurement of differential rates of C¹⁴O₂ evolution from specifically labeled ¹⁴C-glucose substrates, and by measurements of H₂ evolution during anaerobic growth. Catabolite repression measured in relation to steady-state growth rates indicated that the repression mechanism may in fact be a direct consequence of a cell's energy balance, as dictated by the production from pyruvate of "high-energy" molecules such as adenosine triphosphate or acetyl-coenzyme A. The apparent involvement of pyruvate metabolism in both the energetics and the expression of catabolite repression in E. coli is consistent with this view.

² Present address: Department of Bacteriology, University of California, Los Angeles.

¹ Contribution from the Department of Microbiology, North Carolina Agricultural Experiment Station, Raleigh. Published with the approval of the Director of Research as paper no. 2284 of the Journal Series.