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Cloning and sequence analysis of a plasmid replicon from Lactococcus lactis subsp. cremoris FG2
Chun-Qiang Liu1, Kangmin Duan, Noel W. Dunn
1Cooperative Research Centre for Food Industry Innovation, Department of Biotechnology, University of New South Wales, Sydney 2052, Australia.
The Journal of General and Applied Microbiology
|April 1, 1997
Summary
Researchers identified a functional theta replication mechanism in Lactococcus lactis. This involves a specific replicon region encoding a replication protein (Rep) and an origin of replication (ori) essential for plasmid stability.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Plasmids are crucial for bacterial adaptation and genetic exchange.
- Understanding plasmid replication mechanisms is key to genetic engineering of bacteria like Lactococcus lactis.
Purpose of the Study:
- To isolate and characterize a novel replication region from a Lactococcus lactis subsp. cremoris FG2 plasmid.
- To elucidate the functional components and replication mechanism of this identified replicon.
Main Methods:
- Cloning of a 4.8-kb XbaI fragment into a replication probe vector.
- Transformation into Lactococcus lactis LM0230.
- DNA sequencing and PCR subcloning to confirm functional replicon activity.
Main Results:
- A 1.8-kb functional replicon was identified, comprising an open reading frame for a putative replication protein (Rep) and an origin of replication (ori).
- The ori region contains characteristic motifs, including iterated sequences and direct/inverted repeats, essential for replication.
- The identified replicon exhibits homology with known lactococcal theta replicons, suggesting a theta-replicating mechanism.
Conclusions:
- A novel theta replication mechanism was characterized in Lactococcus lactis.
- The identified replicon, including the Rep protein and ori sequence, is essential for plasmid replication in L. lactis.
- This finding contributes to the understanding of plasmid biology in lactic acid bacteria.