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Insertion specificity and trans-activation of IS801
G Y Richter1, K Björklöf, M Romantschuk
1Department of Biology, Southern Oregon University, Ashland, USA.
Molecular & General Genetics : MGG
|December 31, 1998
Summary
The IS801 transposable element from Pseudomonas syringae exhibits relaxed target specificity in E. coli, inserting near GAAC tetramers. Its transposase shares homology with other bacterial transposases, suggesting a common mechanism in transposition.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- The transposable element IS801 was identified in the plasmid pMMC7105 of Pseudomonas syringae pv. phaseolicola.
- Transposable elements play crucial roles in genome evolution and gene regulation.
Purpose of the Study:
- To characterize the transposition mechanism and target specificity of the IS801 element in Escherichia coli.
- To investigate the relationship between IS801 transposase and other known transposases.
Main Methods:
- Transposition assays in E. coli using IS801 on a plasmid target.
- Sequence analysis of target sites flanking IS801 insertions.
- Comparative amino acid sequence analysis of IS801 transposase with other transposases.
Main Results:
- IS801 demonstrates relaxed target specificity in E. coli, with a preference for tetrameric sequences homologous to its left terminus (GAAC).
- Identified target sequences include GAAC, GGAC, CAAG, and CGAC.
- The transposase is functionally and physically separable from the transposing unit, allowing for 'trans' transposition.
- IS801 transposase shares amino acid homology with transposases from E. coli elements IS91 and IS1294, including conserved motifs found in rolling-circle replicases.
Conclusions:
- IS801 is a novel transposable element with unique target selection properties.
- The findings suggest a potential link between IS801 transposition and rolling-circle replication mechanisms.
- The study provides insights into the diversity and evolution of bacterial transposable elements.