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Nucleotide sequence and analysis of conjugative plasmid pVT745
1School of Dentistry, Indiana University, Indianapolis, Indiana 46202, USA. dgalli@iupui.edu
Journal of Bacteriology
|February 13, 2001
Summary
The pVT745 plasmid from the periodontal pathogen Actinobacillus actinomycetemcomitans facilitates its own conjugation and mobilizes other plasmids. Its narrow host range is linked to its HAP theta replicon family origins.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Actinobacillus actinomycetemcomitans is a periodontal pathogen.
- Plasmids play crucial roles in bacterial adaptation and virulence.
- Understanding plasmid biology is key to combating bacterial infections.
Purpose of the Study:
- To present the complete nucleotide sequence and genetic map of the pVT745 plasmid.
- To elucidate the functional elements and genetic organization of pVT745.
- To investigate the conjugative transfer capabilities and host range of pVT745.
Main Methods:
- Whole-genome sequencing of the pVT745 plasmid.
- Bioinformatic analysis of the nucleotide sequence to identify open reading frames and functional domains.
- Conjugation experiments to assess plasmid transfer and mobilization capabilities.
- Comparative analysis with known plasmid replication systems.
Main Results:
- The 25-kb pVT745 plasmid sequence reveals genes for conjugation, replication, and stability, with significant homology to known conjugation proteins.
- pVT745 derivatives successfully mobilized a coresident plasmid and mediated self-transfer among A. actinomycetemcomitans strains.
- Efficient intergeneric transfer to Escherichia coli required the presence of an E. coli origin of replication.
- The plasmid harbors 16 open reading frames encoding proteins of unknown function and a conserved replication region belonging to the HAP theta replicon family.
- pVT745 exhibits a narrower host range than other HAP family replicons, and homologous sequences are found in A. actinomycetemcomitans chromosomes.
Conclusions:
- pVT745 possesses a functional conjugation system and a conserved replication origin within the HAP theta replicon family.
- The plasmid's narrow host range and chromosomal homologs suggest specific evolutionary and dissemination pathways within A. actinomycetemcomitans populations.
- Further research into the unknown open reading frames may reveal novel functions relevant to bacterial pathogenesis or plasmid biology.