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Rolling circle-replicating plasmids from gram-positive and gram-negative bacteria: a wall falls
G del Solar1, M Moscoso, M Espinosa
1Centro de Investigaciones Biológicas, CSIC, Madrid, Spain.
Molecular Microbiology
|May 1, 1993
Summary
Rolling circle replication is a common mechanism in bacteria, found in both Gram-positive and Gram-negative hosts. A unique plasmid family utilizes this method, featuring distinct regulatory circuits for replication control.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Rolling circle replication (RCR) is a mechanism used by small plasmids and bacteriophages.
- Previously, RCR was thought to be primarily in Gram-positive bacteria and Gram-negative bacteriophages.
- Recent findings reveal RCR is widespread across eubacteria.
Purpose of the Study:
- To review a specific family of related promiscuous plasmids that utilize rolling circle replication.
- To highlight their unique replication features and regulatory mechanisms.
- To discuss their prevalence in both Gram-positive and Gram-negative bacteria.
Main Methods:
- Literature review of studies on rolling circle-replicating plasmids.
- Comparative analysis of plasmid sequences and replication proteins.
- Examination of regulatory elements controlling replication.
Main Results:
- A conserved family of RCR plasmids exists across diverse bacterial hosts (Gram-positive and Gram-negative, including Helicobacter).
- These plasmids share homologous leading-strand origins and initiator proteins.
- Unique features include directly repeated sequences at the plus origin and specific regulatory circuits involving antisense RNA and transcriptional repressors.
Conclusions:
- The characterized plasmid family exhibits a unique replication strategy among RCR plasmids.
- These plasmids demonstrate broad host range, replicating autonomously in both Gram-positive and Gram-negative bacteria.
- The findings expand the understanding of RCR mechanisms and plasmid diversity in eubacteria.