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Tn5 insertion specificity is not influenced by IS50 end sequences in target DNA
J K Lodge1, K Weston-Hafer, D E Berg
1Department of Molecular Microbiology, Washington University Medical School, St. Louis, MO 63110.
Molecular & General Genetics : MGG
|August 1, 1991
Summary
The bacterial transposon Tn5 preferentially inserts into specific DNA sites. This study shows that sequences resembling Tn5 ends facilitate insertion at major hotspots, influencing target selection.
Area of Science:
- Molecular Biology
- Genetics
- Bacterial Transposition
Background:
- The bacterial transposon Tn5 exhibits non-random insertion, with preferential targeting of specific DNA sites known as hotspots.
- Previous studies suggested that DNA sequences mimicking the ends of Tn5 or its IS50 elements might guide transposition to these preferred sites.
Purpose of the Study:
- To investigate whether sequences corresponding to the ends of the IS50 element influence the preferential insertion of the bacterial transposon Tn5 into target DNA.
- To determine the role of specific DNA sequences and adenine methylation in Tn5 target site selection.
Main Methods:
- Utilized derivatives of plasmid pBR322 containing IS50 I or O end sequences to test for Tn5 insertion.
- Analyzed Tn5 insertion patterns relative to IS50 end sequences at both major hotspots and distal sites.
- Examined the effect of adenine (dam) methylation on IS50 end sequences on Tn5 transposition.
Main Results:
- Tn5 demonstrated frequent insertion into an IS50 I end located at a major hotspot within the pBR322 plasmid.
- Insertion was not observed at an IS50 I or O end situated 230 base pairs away from the major hotspot.
- Adenine methylation at GATC sequences within the IS50 I end segment did not alter Tn5 insertion preference relative to the IS50 end sequence in the target DNA.
Conclusions:
- The findings support models where Tn5 target site selection is influenced by multiple DNA sequence and conformational features.
- Target selection by Tn5 appears to be a process distinct from the recognition of transposon element ends during transposition.