Density gradient analysis of DNA replicated during Bacillus subtilis sporulation

Orientation of genes in the Bacillus subtilis chromosome

The orientation of 96 genes on the Bacillus subtilis chromosome was deduced by the analysis of published data. Of these genes, 91 were found to be oriented so that their promoters were proximal to the chromosomal replication origin and their transcription termini to the replication terminus. Transcription of these genes would therefore be co-directional with replication. This chromosomal organization is consistent with the hypothesis advanced for Escherichia coli that bacteria avoid head-on collisions between RNA polymerase and DNA replication proteins by the appropriate orientation of their transcription units.