Multiple human L1 elements encode reverse transcriptase activity detected by an in vivo assay in yeast
- Univ. of Pennsylvania School of Medicine, Philadelphia, PA (United States); and others
The L1 family of retrotransposable elements has been shown to cause disease in humans via mutational insertion. Two of these active elements, LRE1 and LRE2, have previously been isolated. Since we are interested in identifying additional L1 elements with the potential to retrotranspose, we isolated L1.3, a full-length element with close similarity to LRE1, and 17 other full-length elements (flL1s) with sequence similarities to active L1s. Utilizing an in vivo assay in S. cerevisiae, the reverse transcriptase (RT) activity encoded by the second open reading frame (ORF2) of L1 elements can be semi-quantitatively determined. Although the activity is highly variable from element to element, the ORF2s of LRE1, LRE2, and L1.3 all encode RT activity. In addition, we have discovered that at least four of nine flL1 elements tested to date encode a functional RT, and thus may have the potential to retrotranspose in the human genome. Comparison of the amino acid sequences of the functional and non-functional L1 RTs should not only demonstrate which residues are essential for L1 RT activity, but also aid in the isolation of additional active L1 elements in the human genome. Additionally, using this assay we have found that mutations in the primer binding site of the yeast retrotransposon Ty1 abolish the function of Ty1 RT but not L1 RT. In summary, our data indicate that a number of human L1 elements encode RT activity and the mechanism of its action differs from that encoded by LRT-containing elements and retroviruses.
- OSTI ID:
- 133451
- Report Number(s):
- CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0179
- Journal Information:
- American Journal of Human Genetics, Vol. 55, Issue Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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