New cluster of ribosomal genes in Bacillus subtilis with regulatory role in sporulation

Abstract

STUDIES of the onset of sporulation in Bacillus subtilis can provide information of value to the study of differentiation in general. Little is known about the molecular mechanisms involved in initiating sporulation, or any other developmental process. Mutations at any one of nine distinct genetic loci may block sporulation in B. subtilis at early stages without affecting vegetative growth1,2. These mutations are pleiotropic, in that they are not only blocked in sporulation but are also impaired, to various degrees, in stage 0 functions such as antibiotic and protease production, competence for transformation, and sensitivity to surface active antibiotics and phage3. We have examined the ribosomal composition of these stage 0 mutants and of the same mutants bearing an additional mutation in another locus, abrB, that results in suppression of the pleiotropic mutant phenotype without suppressing the sporulation defect. We report here that abrB mutations define a new cluster of ribosomal protein genes, with the origin proximal to the main group of ribosomal genes. These findings demonstrate the involvement of ribosomes in the control of early stages of the sporulation cycle.