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IS257-mediated cointegration in the evolution of a family of staphylococcal trimethoprim resistance plasmids
A Leelaporn1, N Firth, I T Paulsen
1School of Biological Sciences, University of Sydney, New South Wales, Australia.
Abstract:
Analyses of the Staphylococcus epidermidis multiresistance plasmids pSK697 and pSK818 have revealed them to be closely related to the trimethoprim resistance plasmid pSK639, also isolated from S. epidermidis. pSK697 and pSK818 were found to contain a cointegrated copy of a second plasmid related to the S. epidermidis multidrug antiseptic and disinfectant resistance plasmid pSK108 and the S. aureus tetracycline resistance plasmid pT181, respectively. In contrast to pSK639, both plasmids were found to contain a third copy of IS257, such that the integrated plasmids in both cases are flanked by a copy of this element. This organization and the presence of duplicated sequences at the extremities of the integrated plasmids implicate IS257 in the formation of these cointegrate plasmids. Sequence analysis of the IS257 elements from these plasmids has provided insights into the probable mechanism of cointegration, viz., nonresolved replicative transposition of IS257.
Insights
Two Staphylococcus epidermidis plasmids, pSK697 and pSK818, show cointegration likely mediated by the IS257 element. This finding offers insights into the mechanism of cointegrate plasmid formation in bacteria.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Staphylococcus epidermidis is a significant pathogen, often carrying antibiotic resistance plasmids.
- Understanding plasmid structure and mobility is crucial for combating bacterial infections.
Purpose of the Study:
- To analyze the structure of Staphylococcus epidermidis plasmids pSK697 and pSK818.
- To investigate the role of the IS257 element in the formation of cointegrate plasmids.
Main Methods:
- Plasmid DNA analysis
- Sequence analysis of IS257 elements
- Comparative genomics
Main Results:
- Plasmids pSK697 and pSK818 are related to known trimethoprim and multidrug resistance plasmids.
- Both plasmids contain cointegrated elements flanked by IS257.
- IS257 is implicated in the formation of these cointegrate plasmids via nonresolved replicative transposition.
Conclusions:
- The IS257 insertion sequence plays a key role in the formation of cointegrate plasmids in Staphylococcus epidermidis.
- The mechanism involves nonresolved replicative transposition of IS257.
- This study enhances understanding of plasmid evolution and antibiotic resistance dissemination.