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Transmissible toxin (hemolysin) plasmid in Streptococcus faecalis and its mobilization of a noninfectious drug
Abstract:
Streptococcus faecalis strain DS-5 has been shown previously to contain three plasmids, pAMalpha1, pAMbeta1, and pAMgamma1. Mixed incubation of DS-5 with strain JH2-2, a plasmid-free S. faecalis recipient, results in the transfer of pAMalpha1 (which determines resistance to tetracycline) and/or pAMgamma1. Analyses of recipients carrying various combinations of these plasmids have revealed the pAMgamma1 codes for toxin (hemolysin) production and two bacteriocin activities. JH2-2 strains carrying both pAMalpha1 and pAMgamma1, or pAMgamma1 only, can donate their plasmids to other recipients, whereas strains carrying only pAMalpha1 cannot serve as donors. This indicates that pAMgamma1 actually mobilizes the otherwise nontransferable pAMalpha1.
Insights
Streptococcus faecalis strain DS-5 harbors three plasmids. Plasmid pAMgamma1 enables the transfer of the tetracycline resistance plasmid pAMalpha1, demonstrating its mobilization capability.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Streptococcus faecalis strain DS-5 contains three plasmids: pAMalpha1, pAMbeta1, and pAMgamma1.
- Previous studies indicated potential transfer of plasmids between S. faecalis strains.
Purpose of the Study:
- To investigate the transferability of plasmids from S. faecalis strain DS-5.
- To determine the functions encoded by the plasmids, specifically pAMgamma1.
- To elucidate the mechanism of plasmid mobilization.
Main Methods:
- Conjugation experiments involving S. faecalis strain DS-5 and a plasmid-free recipient (strain JH2-2).
- Analysis of plasmid content in recipient strains.
- Assessment of plasmid transfer capabilities based on plasmid combinations.
Main Results:
- Mixed incubation resulted in the transfer of pAMalpha1 (tetracycline resistance) and/or pAMgamma1.
- Plasmid pAMgamma1 encodes toxin (hemolysin) production and two bacteriocin activities.
- Strains harboring pAMgamma1 could donate plasmids, while those with only pAMalpha1 could not, indicating pAMgamma1 mobilizes pAMalpha1.
Conclusions:
- Plasmid pAMgamma1 is essential for the mobilization and transfer of the otherwise non-transferable plasmid pAMalpha1 in Streptococcus faecalis.
- pAMgamma1 possesses multiple functional traits, including toxin production and bacteriocin activities.