Characterization of a thermosensitive mutant of Streptomyces hygroscopicus defective in both DNA and RNA syntheses.

A stable temperature sensitive mutant of Streptomyces hygroscopicus JA6599 defective in both DNA and RNA syntheses is described. The mutant ts35 is characterized by an immediate stop of DNA synthesis and continued protein synthesis after transfer to restrictive temperature. The reinitiation of DNA synthesis begins immediately after a return to the permissive temperature. This kinetics of macromolecular synthesis at restrictive temperature appears to share similarities with a defect in the DNA elongation process, as described for Escherichia coli (Carl 1970, Hanna and Carl 1975). The simultaneous stop of both DNA and RNA syntheses may be caused by an additional mutational event affecting also the RNA synthesis. The data were discussed with respect to similar results in E. coli.