Application of the mini-mu phage for the isolation of lac transcriptional fusions in Bacillus subtilis genes

L-cysteine biosynthesis in Bacillus subtilis: identification, sequencing, and functional characterization of the gene coding for phosphoadenylylsulfate sulfotransferase

Random Tn917 mutagenesis of Bacillus subtilis followed by selection of lipoic acid auxotrophs led to the isolation of the cysH gene. The gene was sequenced and found to encode a phosphoadenylylsulfate sulfotransferase with a molecular mass of 27 kDa. Expression of lacZ fused to the cysH promoter was repressed by cysteine and sulfide and induced by sulfur limitation, indicating that cysH is controlled at the level of transcription.

DNA supercoiling and thermal regulation of unsaturated fatty acid synthesis in Bacillus subtilis

Bacillus subtilis growing at 37 degrees C synthesizes, almost exclusively, saturated fatty acids. However, when a culture growing at 37 degrees C is transferred to 20 degrees C, the synthesis of unsaturated fatty acids is induced. The addition of the DNA gyrase inhibitor novobiocin specifically prevented the induction of unsaturated fatty acid synthesis at 20 degrees C. Furthermore, it was determined that plasmid DNA isolated from cells growing at 20 degrees C was significantly more negatively supercoiled than the equivalent DNA isolated from cells growing at 37 degrees C. The overall results agree with the hypothesis that an increase in DNA supercoiling associated with a temperature downshift could regulate the unsaturated fatty acids synthesis in B. subtilis.