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Factors that affect transposition mediated by the Tn21 transposase
J Grinsted1, C Martin, F de la Cruz
1Department of Microbiology, University of Bristol, United Kingdom.
Plasmid
|July 1, 1988
Summary
The Tn21 transposase efficiently mediates transposition on homologous inverted repeats (IRs), with activity varying based on IR sequence. The Tn501 transposase showed no measurable transposition activity in this study.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- Transposable elements, such as transposons, are mobile genetic elements that play a significant role in genome evolution and plasticity.
- Transposon activity is often mediated by specific enzymes called transposases, which recognize and act on characteristic DNA sequences called inverted repeats (IRs).
Purpose of the Study:
- To investigate the substrate specificity of the Tn21 transposase in one-ended transposition reactions.
- To compare the activity of Tn21 transposase on different inverted repeat (IR) sequences from related transposons.
- To assess the transposition activity of the Tn501 transposase on various plasmid-borne IRs.
Main Methods:
- Quantification of one-ended transposition frequencies mediated by purified Tn21 transposase.
- In vitro assays using plasmids containing 38-bp inverted repeat (IR) sequences from Tn21, Tn501/Tn1721, and Tn2501.
- Analysis of transposase activity on plasmids with single or two inverted copies of IRs.
Main Results:
- The Tn21 transposase demonstrated activity on IRs from Tn21, Tn501/Tn1721, and Tn2501, with higher efficiency on homologous Tn21 IRs.
- Differences in transposition efficiency were amplified when using plasmids with two inverted copies of the IRs.
- The Tn21 transposase did not recognize the IR sequence of Tn3.
- The Tn501 transposase exhibited no measurable one-ended transposition activity with any of the tested plasmids, including those containing its own IR.
Conclusions:
- The Tn21 transposase exhibits sequence specificity for its cognate inverted repeat (IR) sequences.
- The Tn501 transposase appears to lack detectable one-ended transposition activity under the conditions tested, suggesting potential differences in its catalytic mechanism or substrate recognition compared to Tn21.
- These findings contribute to understanding the molecular mechanisms and specificity of transposition for different bacterial transposons.