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Complete nucleotide sequence and characterization of pUA140, a cryptic plasmid from Streptococcus mutans
1Department of Oral Biology, School of Dentistry, University of Alabama at Birmingham, AL 35294, USA.
Plasmid
|October 10, 2001
Summary
Streptococcus mutans strain UA140 contains a cryptic plasmid, pUA140, that replicates via rolling circle mechanism. This plasmid shows unique characteristics differentiating it from the pT181 family.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Streptococcus mutans is a key pathogen in dental caries.
- Plasmid DNA is found in approximately 5% of S. mutans strains.
- Understanding plasmid replication mechanisms is crucial for microbial genetics.
Purpose of the Study:
- To characterize the cryptic plasmid pUA140 from Streptococcus mutans strain UA140.
- To elucidate the replication mechanism of pUA140.
- To compare pUA140 with other known plasmid families.
Main Methods:
- Plasmid DNA isolation and characterization.
- Open reading frame (ORF) identification and analysis.
- Sequence homology searches and replication origin identification.
- Detection of single-stranded DNA intermediates.
Main Results:
- pUA140 is a 5.6-kb cryptic plasmid with a G+C content of 32.7%.
- Five ORFs were identified, with ORF1 showing similarity to a replication protein (Rep).
- pUA140 possesses double-stranded and single-stranded origins of replication, characteristic of rolling circle replication.
- A single-stranded DNA intermediate was detected, confirming rolling circle replication.
Conclusions:
- pUA140 replicates via the rolling circle mechanism.
- pUA140 exhibits distinct features compared to other pT181 family plasmids.
- Further research is needed to fully understand the unique aspects of pUA140 replication.