Mobilizable Rolling-Circle Replicating Plasmids from Gram-Positive Bacteria: A Low-Cost Conjugative Transfer

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Horizontal gene transfer (HGT) in bacteria relies on conjugation, a process where plasmids are transferred between cells.
• Mobilizable plasmids, unlike self-transmissible ones, require auxiliary functions from conjugative elements for transfer.
• Mobilizable plasmids are prevalent in natural environments, suggesting efficient replication and mobilization mechanisms contribute to their promiscuity.

Purpose of the Study:

• To review information on small mobilizable plasmids from Gram-positive bacteria that replicate via the rolling-circle mechanism.
• To highlight the streptococcal plasmid pMV158 as a model system for studying plasmid promiscuity.
• To discuss strategies for assessing and inhibiting plasmid transfer, and review biotechnological applications.

Main Methods:

• Review of existing literature on rolling-circle replicating mobilizable plasmids.
• Analysis of the pMV158 plasmid's mobilization module (MOBV) and its replication mechanism.
• Discussion of methods for evaluating plasmid transfer efficiency and inhibition.

Main Results:

• Two families of small rolling-circle replicating mobilizable plasmids from Gram-positive bacteria are identified.
• The pMV158 plasmid's promiscuity is linked to two origins of lagging strand synthesis within its replicon.
• The MOBV mobilization module is widely distributed among mobilizable plasmids.

Conclusions:

• Replication and mobilization are crucial for plasmid promiscuity and prevalence in nature.
• The pMV158 model provides insights into the mechanisms driving mobilizable plasmid spread.
• Understanding these mechanisms can inform biotechnological applications and strategies to control plasmid transfer.