Identification of a suppressor sequence for DNA replication in the replication origin region of the Bacillus subtilis chromosome.

Publisher Website
Google Scholar
Abstract
The 1st replicating fragment of the B. subtilis chromosome, B7, inhibited the replication of the plasmid that carried this fragment. In earlier work using sequential cleavage by AluI, the suppressor function was located within a 489 base pair segment. The nucleotide sequence of the entire segment was now determined. The sequence is characterized by 2 promoter-like structures and severalputative recognition sequences, such as termination signals, 2-fold symmetries, inverted repeats, and repeats. By means of sequential cleavage with exonuclease BAL-31, the essential region for suppression was located in a 200 base pair region that contains the 2 promoters with the same orientation. Specific transcription was produced in vitro by using B. subtilis or Escherichia coli RNA polymerases. The transcription was mostly from the 2nd promoter. Elimination of the -35 region of the 2nd promoter dramatically affected both inhibitory activity and in vitro transcription, suggesting that the transcriptional activity of the 2nd promoter is involved in the cis-inhibition of DNA replication. The significance of the suppressor sequence in the region of the replication origin of the B. subtilis chromosome is discussed.