Ein Strukturgen-Komplex für den Pyruvat-Dehydrogenase-Komplex von Escherichia coli K 12.

Acetateless mutants of Escherichia coli K 12 lacking the enzymatic activities either of the carboxylase, the lipoic reductase-transacetylase or of all components of the pyruvate dehydrogenase complex are shown to be the consequence of mutations in the closely linked structural genes for the constituent enzymes of the enzyme complex. This genetic segment (the acetate locus = Ac) was found on the E. coli chromosome between the leucine and T loci. Acetate and leucine loci are transduced jointly by the phage Plkc. The preparation is described of double mutants carrying two genetic lesions in the pyruvate dehydrogenase structural gene cluster. The mutant sites of 0-type strains have been localized in a part of the carboxylase structural gene corresponding to the left extremity (nearest the leucine locus) of the acetate locus. Studies on possible genetic relationships between the pyruvate and α-ketoglutarate dehydrogenases (which regarding the individual reactions catalyzed are very similar and partly identical) revealed that the two α-keto acid dehydrogenases most likely do not share any genetic determinant. [ABSTRACT FROM AUTHOR]