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Involvement of E. coli dcm methylase in Tn3 transposition
1Department of Biology, Fu-Jen University, Taipei, Taiwan, Republic of China.
Proceedings of the National Science Council, Republic of China. Part B, Life Sciences
|October 1, 1989
Summary
DNA methyltransferases influence Tn3 transposition, with deoxycytosine methylase enhancing transposition frequency. Tn3 transposase also appears to modify DNA, affecting restriction enzyme recognition sites.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- Transposable elements like Tn3 play crucial roles in genome dynamics.
- DNA methylation is a key epigenetic mechanism influencing gene expression and DNA replication.
- The interplay between DNA methylation and transposition is not fully understood.
Purpose of the Study:
- To investigate the impact of DNA methyltransferases on Tn3 transposition in E. coli.
- To determine if Tn3 transposase itself possesses DNA modification activity.
Main Methods:
- Comparative analysis of Tn3 transposition frequencies in wild-type and mutant E. coli strains with varying DNA methyltransferase activities.
- Introduction of the EcoRII methylase gene into dcm- cells to assess its effect on transposition.
- Analysis of plasmid DNA methylation status using restriction enzyme digestion assays.
Main Results:
- Tn3 transposition was significantly higher in deoxycytosine methylase-positive (dcm+) cells compared to dcm- mutants.
- Introduction of EcoRII methylase into dcm- cells increased Tn3 transposition frequency.
- Plasmid DNA from E. coli expressing Tn3 transposase showed altered susceptibility to restriction enzymes, suggesting DNA modification.
Conclusions:
- Deoxycytosine methylation appears to create a preferred target for Tn3 transposition.
- Tn3 transposase exhibits DNA modification activity, potentially altering recognition sequences for specific restriction enzymes.