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An in vivo transposase-catalyzed single-stranded DNA circularization reaction
1Laboratoire de Microbiologie et Génétique Moléculaires, UPR9007 du Centre National de la Resherche Scientifique (CNRS), Toulouse, France.
Genes & Development
|November 15, 1995
Summary
Bacterial insertion sequence IS911 transposase creates a "figure-eight" DNA molecule during transposition. This intermediate suggests a novel mechanism for IS911 circle formation via sequential strand processing.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- Bacterial insertion sequences (IS) are mobile genetic elements.
- IS911 transposition involves its transposase enzyme.
- Transposition typically results in element excision and integration.
Purpose of the Study:
- To elucidate the molecular mechanism of IS911 transposition.
- To investigate the role of IS911 transposase in DNA processing.
- To characterize intermediate structures formed during IS911 excision.
Main Methods:
- In vivo expression of IS911 transposase in a plasmid system.
- Analysis of DNA structures using molecular biology techniques.
- Kinetic studies to determine the temporal relationship of intermediates.
Main Results:
- IS911 transposase generates a "figure-eight" DNA intermediate.
- This intermediate involves single-strand cleavage, transfer, and ligation at IS911 ends.
- Figure-eight molecules accumulate before and disappear before transposon circles.
Conclusions:
- IS911 transposase exhibits single-strand cleavage activity, similar to retroviral integrases.
- Figure-eight molecules are likely precursors to IS911 circular forms.
- IS911 excision may proceed via sequential strand circularization rather than double-strand cleavage.