Characterization of carbamoyl phosphate synthetase of <i>Streptomyces </i>spp.

Abstract

Carbamoyl phosphate synthetase (CPS) activity in <i>Streptomyces lividans </i>was repressed (70%) by addition of arginine and uracil in the growth medium. Enzyme activity was also inhibited by UMP and activated by ornithine and IMP. Pattern of inhibition and activation was similar irrespective of whether the cells were grown in medium supplemented with arginine or with uracil. A mutant of <i>S</i>. <i>coelicolor </i>with dual auxotrophy for arginine and uracil possessed only about 20% of CPS activity compared to the wild-type strain. An activity staining protocol has been developed for CPS enzyme. Using this method a single CPS band has been observed in the crude extracts of <i>Escherichia coli </i>as well as in <i>S</i>. <i>lividans. </i>Taken together, our results supported the conclusion that <i>Streptomyces </i>species might possess a single CPS enzyme unlike other gram-positive bacteria, which show the presence of two pathway-specific isozymes (<i>Bacillus</i>)<i> </i>or none (<i>Lactobacillus </i>and <i>Leuconostoc</i>)<i>.</i>