Effect of ca on the synthesis of deoxyribonucleic Acid in virulent and avirulent yersinia.

Virulent and potentially virulent cells of Yersinia (Pasteurella) pestis produce virulence or V and W antigens (VW(+)) but remain static at 37 C during aeration in enriched Ca(2+)-deficient media containing 0.02 m Mg(2+). In this environment, which simulates mammalian intracellular fluid, VW(+) cells possessed a functional cytoplasmic membrane as judged by concentration of (14)C-isoleucine, release of (32)P, and consumption of oxygen at rates comparable to those of dividing cells cultivated with Ca(2+). Furthermore, rates of protein and ribonucleic acid synthesis were essentially identical in dividing and static VW(+) cells and in mutant VW(-) organisms. However, the rate of deoxyribonucleic acid (DNA) synthesis in static cells was about 10% of that observed in dividing organisms. Accordingly, bacteriostasis of VW(+) cells in the simulated intracellular environment is evidently caused by reactions directly associated with cessation of DNA synthesis rather than by alterations in the regulatory capacity of the cytoplasmic membrane.