In vitro complementation of Bacillus subtilis and Escherichia coli 2-oxoglutarate dehydrogenase complex mutants and genetic mapping of B. subtilis citK and citM mutations

Abstract


The 2-oxoglutarate dehydrogenase complex of the tricarboxylic acid cycle (TCA) consists of multiple copies of 3 different subenzymes; E1, E2 and E3. The E3 subenzyme is also a component of the pyruvate dehydrogenase complex. Bacillus subtilis 2-oxoglutarate dehydrogenase mutants were studied. The mutants defective in E1, E2 and E3 subenzyme activity, respectively, could be separated into 3 groups by biochemical complementation analyses. The groups correspond to the citK, citM and citL genes. A B. subtilis subenzyme defect, probably E1, could be complemented with the corresponding Escherichia coli wild-type subenzyme and vice versa. Mutations in citK and citM are closely linked. The gene order kauA--- ---citK-citM was determined from 3-factor transformation crosses. It is concluded that the gene organization and the subenzyme structure of the 2-oxoglutarate dehydrogenase complex are similar in B. subtilis and E. coli.