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Molecular analysis of the replication region of the theta-replicating plasmid pUCL287 from Tetragenococcus
A Benachour1, J Frère, S Flahaut
1Laboratoire de Microbiologie de l'Environnement, IRBA, Université de Caen, France.
Abstract:
The complete nucleotide sequence of the 8.7-kb theta-replicating plasmid pUCL287 from Tetragenococcus halophilus (formerly Pediococcus halophilus) ATCC33315 has been determined. The replication region was identified and analyzed. Its nucleotide sequence contains an untranslated region, the replication origin, followed by two open reading frames (ORFs) encoding two proteins of 311 (RepA287) and 168 (RepB287) amino acids, respectively. Evidence is presented to show that RepA287 represents the plasmid replication protein. RepB287, which is non-essential for replication, is involved in the plasmid copy-number control and segregational stability. The roles of lactococcal proteins homologous to RepB287 have not been defined so far. Nevertheless, the structural organization of the pUCL287 replication region is remarkably similar to those of well known theta-replicating lactococcal plasmids despite the absence of homology of the replication origin and of the replication protein, and this suggests that pUCL287 uses the same mechanism of replication. Nucleotide sequence comparisons show that pSMB74, a pediococcal plasmid encoding bacteriocin production, is a member of the pUCL287 replicon family.
Insights
The complete nucleotide sequence of the theta-replicating plasmid pUCL287 from Tetragenococcus halophilus was determined. Its replication region contains genes for replication and copy-number control proteins, similar to lactococcal plasmids.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Tetragenococcus halophilus is a halophilic bacterium.
- Plasmids play crucial roles in bacterial adaptation and evolution.
- Theta-replicating plasmids are common in Gram-positive bacteria.
Purpose of the Study:
- To determine the complete nucleotide sequence of the theta-replicating plasmid pUCL287.
- To identify and analyze the replication region of pUCL287.
- To understand the functions of the proteins encoded by the replication region.
Main Methods:
- DNA sequencing
- Bioinformatic analysis
- Sequence comparison
Main Results:
- The 8.7-kb plasmid pUCL287 sequence was determined.
- Two open reading frames (ORFs) were identified, encoding RepA287 (replication protein) and RepB287 (copy-number control).
- The replication region shares structural similarity with lactococcal theta-replicating plasmids, suggesting a conserved replication mechanism.
Conclusions:
- RepA287 is essential for pUCL287 replication.
- RepB287 is involved in plasmid copy-number control and stability.
- pUCL287 belongs to a replicon family that includes pediococcal plasmids like pSMB74.