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Replication and segregational stability of Bacillus plasmid pBAA1
K M Devine1, S T Hogan, D G Higgins
1Department of Genetics, Trinity College, Dublin, Ireland.
Journal of Bacteriology
|February 1, 1989
Summary
A novel cryptic plasmid, pBAA1, was discovered in industrial Bacillus. This stable, low-copy-number plasmid replicates via a rolling-circle mechanism, crucial for industrial fermentation processes.
Area of Science:
- Microbiology
- Molecular Biology
- Biotechnology
Background:
- Cryptic plasmids can be valuable genetic tools in industrial microorganisms.
- Understanding plasmid stability and replication is essential for biotechnological applications.
- Bacillus strains are widely used in industrial fermentation.
Purpose of the Study:
- To characterize the cryptic plasmid pBAA1 identified in an industrial Bacillus strain.
- To identify the minimal replicon and essential replication control elements of pBAA1.
- To investigate the replication mechanism and stability factors of pBAA1.
Main Methods:
- Plasmid DNA isolation and characterization.
- Subcloning and functional analysis of the minimal replicon.
- Sequence analysis and comparison with known plasmids.
- Segregational stability assays.
Main Results:
- The 6.8 kb cryptic plasmid pBAA1 was identified with a low copy number (approx. 5 per chromosome).
- A 1.4 kb fragment containing the minimal replicon, copy number control, and potential maintenance functions was identified.
- pBAA1 replicates via a rolling-circle mechanism, characteristic of small gram-positive plasmids.
- A specific sequence essential for efficient plus-strand conversion was identified, and its deletion caused instability.
Conclusions:
- pBAA1 is a stable, partition-proficient plasmid suitable for industrial applications.
- The identified minimal replicon provides insights into plasmid replication and maintenance.
- The rolling-circle replication mechanism and specific sequence are key to pBAA1's stability.