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Identifying related L1 retrotransposons by analyzing 3' transduced sequences
Suzanne T Szak1, Oxana K Pickeral, David Landsman
1National Center for Biotechnology Information (NCBI), National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
Genome Biology
|May 8, 2003
Summary
L1 retrotransposons mobilize DNA, including flanking sequences via 3' transduction. Our study identified L1-TD elements, suggesting internal priming during reverse transcription, and indicates transduction may be less common than presumed.
Area of Science:
- Genomics
- Molecular Biology
- Bioinformatics
Background:
- The human genome contains a substantial fraction of L1 retrotransposon sequences.
- L1-encoded proteins facilitate the transposition of other repetitive elements and processed pseudogenes.
- L1 retrotransposons can mobilize adjacent 3'-flanking DNA through a process termed 3' transduction.
Purpose of the Study:
- To computationally identify and analyze human DNA sequences mobilized via L1-mediated 3' transduction.
- To reconstruct L1 element families and understand their evolutionary relationships.
- To investigate the mechanism and frequency of L1-mediated 3' transduction.
Main Methods:
- Computational analysis of human genomic DNA sequences.
- Identification of L1 elements with transduction-derived sequences (L1-TD).
- Reconstruction of parent-progeny L1 element families.
Main Results:
- Identified L1-TD precursors, enabling reconstruction of L1 element families.
- Most L1-TDs were found in duplicated genomic regions, not representing unique insertions.
- Some L1-TDs lacked polyadenylation signals, but sequence alignments ended in A-rich tracts.
Conclusions:
- L1-TD integration may involve internal priming at A-rich sequences downstream of the L1 3' untranslated region.
- L1-mediated transduction might occur less frequently in the human genome than previously estimated.
- Segmental genomic duplications complicate accurate frequency estimations of L1-mediated transduction.