ADP‐Ribosylation of DNA‐Dependent RNA Polymerase of Escherichia coli by an NAD+: Protein ADP‐ribosyltransferase from Bacteriophage T4

Abstract

A protein from bacteriophage T4 responsible for the alteration of host DNA‐dependent RNA polymerase and absent in T4 alt− phage was purified from T4 phage and enriched from T4‐infected cells. It is injected during infection together with the known internal proteins. It has a molecular weight of about 70000 and catalyses the release of nicotinamide and the transfer of the ADP‐ribosyl moiety from NAD+ to arginyl residues of various proteins including itself. RNA polymerase from Escherichia coli accepts ADP‐ribosyl residues in all four subunits; the α subunit reacts with very high specificity. Only half of the α subunits are labelled, 45 with one, 5 % with two residues. The main product shows the same electrophoretic mobility as α subunits altered or modified in vivo. The a subunit in modified RNA polymerase is no acceptor. Copyright © 1975, Wiley Blackwell. All rights reserved