Novel rpoB mutations conferring rifampin resistance on Bacillus subtilis: global effects on growth, competence, sporulation, and germination.

Previously, spontaneous rifampin resistance mutations were isolated in cluster I of the rpoB gene, resulting in amino acid replacements (Q469R, H482R, H482Y, or S487L) in the Bacillus subtilis RNA polymerase beta subunit (W. L. Nicholson and H. Maughan, J. Bacteriol. 184:4936-4940, 2002). In this study, each amino acid change in the beta subunit was observed to result in its own unique spectrum of effects on growth and various developmental events, including sporulation, germination, and competence for transformation. The results thus establish the important role played by the RNA polymerase beta subunit, not only in the catalytic aspect of transcription, but also in the regulation of major developmental events in B. subtilis.