Bacillus subtilis RNA Polymerase Mutants Temperature-sensitive for Sporulation

Abstract

INTRODUCTION
Changes in the structure and specificity of DNA-dependent RNA polymerase during sporulation of Bacillus subtilis may contribute to the altered pattern of RNA synthesis known to occur during this developmental period (DiCioccio and Strauss 1973; Sumida-Yasumoto and Doi 1974; Pero, Nelson and Losick 1975). The sigma subunit of vegetative RNA polymerase does not copurify with RNA polymerase extracted from sporulating cells (Tjian and Losick 1974). This phenomenon coincides with the loss of sigma activity in extracts of sporulating cells, causing a change in RNA polymerase template specificity (Losick and Sonenshein 1969; Linn et al. 1973; Brevet 1974; Tjian and Losick 1974). Relative to vegetative extracts, sporulation extracts have reduced activity with phage φe DNA as template but have normal activity with the synthetic template poly(dA·dT). Loss of sigma binding and activity in sporulating cells may be due to the presence of a metabolically unstable antagonist (Segall et al. 1974).

In addition to lacking sigma, RNA polymerase extracted from sporulating cells differs from its vegetative counterpart in that it contains a novel, large polypeptide, described as having a molecular weight of 70,000–85,000 (Greenleaf, Linn and Losick 1973; Linn, Greenleaf and Losick 1975) or 95,000 (Nishimoto and Takahashi 1974), as well as one or more polypeptides in the 20,000–27,000 MW range (Fukuda et al. 1975; Linn, Greenleaf and Losick 1975). No sporulation-specific transcription function can as yet be ascribed to these proteins.

By studying mutants resistant to the RNA polymerase-specific drugs rifampin (Rfm) and streptolydigin (Std) it was possible...