The action of 5-azacytidine on bacteria infected with bacteriophage T4

Abstract

1. 1. 5-Azacytidine, in concentrations higher than 0.5 μg/ml, strongly inhibits the production of viable phage particles by bacteria infected with bacteriophage T4. The inhibitory action can be abolished completely by cytidine and mitigated slightly by deoxycytidine. The inhibition becomes irreversible about 3 min after the addition of 5-azacytidine. When added later than 12 min after infection, 5-azacytidine does not interfere with phage maturation. 2. 2. Synthesis of RNA is not affected by 5-azacytidine but synthesis of DNA is strongly inhibited. The inhibition of DNA synthesis cannot be reversed by deoxy-cytidine, but is reversed by cytidine. In un-infected cells 5-azacytidine does not inhibit the synthesis of DNA. 3. 3. When 5-azacytidine is added immediately after infection, total protein synthesis is inhibited only in the late period of phage development; the synthesis of late phage-specific proteins is inhibited, whereas the early enzymes are slightly over-produced. 4. 4. The frequency of genetic recombination is not affected by 5-azacytidine.