THE METABOLISM OF RIBONUCLEIC ACID IN NORMAL AND BACTERIOPHAGE INFECTED ESCHERICHIA COLI

Abstract

The metabolism of ribonulceic acid (RNA) of a glycineless mutant of E. coli B was investigated during growth of the organism and infection with bacteriophage T4r. Glycine-2-C14 incorporation into the purines of the RNA was used as an indicator of RNA metabolism. During growth of labelled, unlnfected cells in an un-labelled medium, no significant amts. of radioactivity were lost from cellular RNA, even though total RNA doubled. Also when unlabelled, uninfected cells were grown in a medium containing glycine-2-C14, the final specific activity of the adenylic and guanylic acids of the RNA was that which one would expect if radioactivity were incorporated only into the newly-synthesized RNA. Apparently the growing organism has the ability to synthesize but degrade intracellular RNA, consequently there is no turnover. RNA could not be converted to DNA during growth. E. coll contain a ribonuclease which degrades the endogenous RNA to dialyzable fragments only after the cells are lysed by sonic vibration or phage. The enzyme is apparently not active in vivo. In confirmation of the work done by others, there was neither turnover nor degradation of the RNA in the infected host during phage multiplication. Since the RNA of the uninfected, growing organism is not subject to degradation, the inertness of the RNA during phage multiplication is a result of the fact that de novo synthesis of RNA has been prevented.