Cloned Bacillus subtilis DNA containing a gene that is activated early during sporulation

An endonuclease restriction fragment of Bacillus subtilis DNA has been identified that contains a gene whose transcription is activated early during the process of spore formation. This 4.4 kilobase (kb) DNA was detected by hybridizing electrophoretically separated Eco R1 restriction fragments with a radioactively labeled RNA of 0.4 kb from sporulating cells. The 4.4 kb B. subtilis DNA was then cloned and amplified in E. coli by insertion into the plasmid vector pMB9. Using the cloned B. subtilis DNA as a hybridization probe, we were able to detect the 0.4 kb transcript in total RNA from pulse-labeled bacteria. In wild-type cells, the gene coding for the 0.4 kb RNA was turned on within the first 30 min of spore formation. Although transcribed normally in a mutant blocked at stage II of spore development, the gene for the 0.4 kb RNA was not turned on in six different mutants blocked at stage 0 of sporulation. We conclude that the cloned B. subtilis DNA contains a gene whose transcription is regulated by events occurring at the onset of spore development.