The In Vitro Transcriptional Specificity of RNA Polymerase Isolated from SP82-infected Bacillus subtilis

Abstract

INTRODUCTION
Several lines of evidence indicate that the development of many phages is controlled at least in part by modification of the host RNA polymerase (reviewed by Chamberlin 1974). One example of this type of regulation is found in Bacillus subtilis infected with either of two related hydroxy-methyluracil-containing phages: SP82 (Spiegelman and Whiteley 1974a) or SPO1 (Duffy and Geiduschek 1973Duffy and Geiduschek 1975; Fox and Pero 1974; Pero, Nelson and Fox 1975; Pero et al. 1975). RNA polymerase isolated from cells infected with either one of these phages differs from the host polymerase with respect to subunit composition and in vitro transcriptional specificity. We have now separated two forms of SP82-modified polymerase, each having a different subunit composition. The in vitro synthesis of RNA by each of these forms has been investigated by comparing the temporal classes of RNA synthesized from the H and L strands of SP82 DNA and the transcription of the deoxycytidylate (dCMP) deaminase gene.

RESULTS AND DISCUSSION
Isolation of Two Forms of the SP82-modified RNA Polymerase
Our initial isolations of RNA polymerase from SP82-infected B. subtilis yielded an enzyme containing the β′, β and α subunits of the host polymerase and one major polypeptide having a lower molecular weight than α, plus trace amounts of two other small polypeptides (Spiegelman and Whiteley 1974a). Modification of the purification procedure resulted in the isolation of an enzyme having larger amounts of the latter two polypeptides, and use of 12.5% polyacrylamide gels resolved three additional polypeptides having molecular weights less than...