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Streptococcus faecalis R plasmid pJH1 contains a pAM alpha 1 delta 1-like replicon
Abstract:
Streptococcus faecalis R plasmid pJH1 did not transform competent strains of Streptococcus sanguis. A hybrid plasmid, pDL310, consisting of virtually all of the S. faecalis hemolysin-bacteriocin plasmid pJH2 and a segment of pJH1 DNA that included the tetracycline resistance determinant, yielded tetracycline-resistant transformants at a frequency of less than 10(-8) transformants per CFU, when it was added to a competent culture of S. sanguis Wicky. Four of the transformants contained a 4.7-kilobase plasmid (pDL316) that transformed strain Wicky at a frequency of 8.6 X 10(-8). Restriction endonuclease digests, agarose gel electrophoresis, and Southern blot hybridizations indicated that pDL316 consisted entirely of pJH1-derived DNA. Additional restriction studies, Southern blot hybridizations, and heteroduplex analyses indicated that pDL316 was very closely related to 4.6-kilobase tetracycline resistance plasmid pAM alpha 1 delta 1, a derivative of 9.0-kilobase S. faecalis plasmid pAM alpha 1.
Insights
Streptococcus sanguis was transformed with a hybrid plasmid containing DNA from Streptococcus faecalis. A smaller, derived plasmid (pDL316) efficiently transformed Streptococcus sanguis, indicating successful gene transfer.
Area of Science:
- Molecular Biology
- Microbial Genetics
- Bacterial Transformation
Background:
- Streptococcus faecalis plasmid pJH1 failed to transform competent Streptococcus sanguis strains.
- Investigating interspecies plasmid transfer is crucial for understanding microbial genetic exchange.
Purpose of the Study:
- To assess the transformability of Streptococcus sanguis using hybrid plasmids derived from Streptococcus faecalis.
- To characterize plasmids obtained from initial transformation attempts and evaluate their transformation efficiency.
Main Methods:
- Construction of a hybrid plasmid (pDL310) combining S. faecalis plasmids pJH2 and pJH1.
- Transformation of competent Streptococcus sanguis Wicky with pDL310.
- Characterization of resulting transformants using restriction endonuclease digestion, agarose gel electrophoresis, Southern blot hybridization, and heteroduplex analysis.
Main Results:
- Initial transformation with pDL310 yielded very low frequencies of tetracycline-resistant transformants (<10(-8) CFU).
- Four transformants harbored a 4.7-kilobase plasmid, pDL316, which demonstrated significantly higher transformation efficiency (8.6 x 10(-8)) in S. sanguis Wicky.
- Molecular analyses confirmed pDL316 comprised entirely of DNA from the S. faecalis pJH1 plasmid and showed close relation to pAMα1δ1.
Conclusions:
- A derivative plasmid, pDL316, originating from Streptococcus faecalis DNA, is capable of efficient transformation in Streptococcus sanguis.
- This study demonstrates the successful transfer and maintenance of specific genetic elements between different Streptococcus species.