Genetic and Biochemical Characterization of Mutants of Bacillus subtilis Defective in Succinate Dehydrogenase

Eleven succinate-accumulating mutants ofBacillus subtilis have been mapped by transformation and transduction crosses and characterized with respect to activities of citric acid cycle enzymes. These mutants could be divided into three genetic groups. Nine of the mutants were found to map betweenargA andleu in thecitF locus. A second group was located betweenlys-1 andtrpC2 and the third group could not be located on theB. subtilis chromosome in extensive transduction crosses. All of thecitF mutants lack detectable succinate dehydrogenase activity, whereas both of the other groups show a reduced level of this enzyme. In addition, most of the mutants in thecitF locus lack cytochromea , whereas the level of this cytochrome is normal in the other two groups. A procedure has been devised for the solubilization of the succinate dehydrogenase from the membrane ofB. subtilis with the non-ionic detergent Brij 58. Some properties of the soluble and bound forms of succinate dehydrogenase are described.