Utilization of subsidiary chromosomal replication terminators in Bacillus subtilis

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Genetics

Background:

• Bacterial DNA replication involves a complex interplay of origins and termination sites.
• The primary replication terminator in Bacillus subtilis is TerI, with TerIII and TerV proposed as subsidiary terminators.
• Understanding terminator utilization is crucial for comprehending genome stability and replication dynamics.

Purpose of the Study:

• To investigate the functional utilization of subsidiary replication terminators (TerIII and TerV) in a Bacillus subtilis merodiploid strain (GSY1127).
• To compare terminator usage in the merodiploid strain with the wild-type B. subtilis 168 strain.
• To confirm the role of TerIII and TerV as backup termination sites.

Main Methods:

• Construction and characterization of a Bacillus subtilis merodiploid strain (GSY1127) with a chromosomal duplication.
• Analysis of replication terminus region location and asymmetry relative to oriC in GSY1127.
• Comparative analysis of TerIII and TerV utilization in GSY1127 versus B. subtilis 168.

Main Results:

• The merodiploid strain GSY1127 exhibits an asymmetric location of the replication terminus region.
• TerIII is significantly utilized in the GSY1127 strain, while TerV shows marginal usage.
• Neither TerIII nor TerV is measurably used in the standard B. subtilis 168 strain, where TerI efficiently arrests forks.

Conclusions:

• TerIII and TerV function as backup replication terminators to the primary TerI site.
• The merodiploid state influences the utilization of subsidiary terminators.
• In B. subtilis 168, replication forks are predominantly arrested at TerI, leading to frequent fork fusion.