Evidence in Favour of the Modification in vivo of RNA Polymerase Subunits during Sporogenesis in Bacillus thuringiensis

Abstract

The subunit composition of RNA polymerase from Bacillus thuringiensis during Sporogenesis has been examined in crude extracts, through immunoprecipitation experiments. Modifications of the different subunits, especially of the β' and sigma subunits were demonstrated and the timing of these modifications have been specified. As regards the origin of these modifications, arguments in favour of the proteolysis in vivo were obtained from such experiments: analysis of labelled RNA polymerase extracted from sporulating cells, mature spores and from mixtures of vegetative and sporulating cells allowed us to exclude neosynthesis or any artefactual modification resulting from a proteolysis in vitro. On the other hand the same experiments revealed the appearence of new components characteristic for sporulating cells: a polypeptide chain of molecular weight 75000 and two new subunits named Y and Z, previously found in the sporal enzyme. In the same way, new components of low molecular weight, associated with RNA polymerase were also detected in vegetative cells infected with phage B 1715 V1.