Replication terminus of the Bacillus subtilis chromosome

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Bidirectional replication of the Bacillus subtilis chromosome normally terminates opposite the replication origin.
• Termination is presumed to occur where replication forks meet due to similar replication rates.

Purpose of the Study:

• To investigate if the DNA sequence at the termination region influences the termination event.
• To determine the latest replicating region in a Bacillus subtilis strain with an asymmetrically positioned termination region.

Main Methods:

• Utilized a merodiploid Bacillus subtilis strain (GSY1127) with a large, nontandem duplication.
• Examined replication order of genetic markers in the modified chromosome.
• Employed pulse-density transfer experiments during synchronous replication for confirmation.

Main Results:

• The normally terminal marker for replication remained a terminal marker in the modified strain.
• This terminal marker replicated later than a marker situated symmetrically opposite the origin.
• Results were consistent across different experimental methods.

Conclusions:

• The Bacillus subtilis chromosome possesses a preferred site for replication termination.
• This preferred site is independent of the replication origin's position.