| Structural highlights
Function
LORF2_HUMAN Has a reverse transcriptase activity required for target-primed reverse transcription of the LINE-1 element mRNA, a crucial step in LINE-1 retrotransposition. Has also an endonuclease activity that allows the introduction of nicks in the chromosomal target DNA. Cleaves DNA in AT-rich regions between a 5' stretch of purines and a 3' stretch of pyrimidines, corresponding to sites of LINE-1 integration in the genome.[1] [2] [3]
Publication Abstract from PubMed
Long interspersed nuclear element-1 (LINE-1 or L1), the only autonomously active retrotransposon in humans today, constitutes a large proportion of the genome and continues to evolve the genome and impact fundamental biological processes. L1 retrotransposition critically depends on its endonuclease and reverse transcriptase subunit open reading frame 2 protein (ORF2p), which targets genomic loci and nicks DNA using an evolutionarily distinct yet not fully understood mechanism. Our structural and biochemical analyses revealed that ORF2p is a structure-dependent endonuclease. It binds a double-stranded DNA region upstream of the nicking site and recognizes a downstream forked or flap structure for efficient DNA nicking. This discovery suggests that L1 mobilization piggybacks on chromosomal processes with noncanonical DNA structure intermediates.
Mechanism of DNA targeting by human LINE-1.,Jin W, Yu C, Zhang Y, Cao C, Xia T, Song G, Cai Z, Xue Y, Zhu B, Xu RM Science. 2025 Oct 9;390(6769):eadu3433. doi: 10.1126/science.adu3433. Epub 2025 , Oct 9. PMID:41066570[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Dombroski BA, Feng Q, Mathias SL, Sassaman DM, Scott AF, Kazazian HH Jr, Boeke JD. An in vivo assay for the reverse transcriptase of human retrotransposon L1 in Saccharomyces cerevisiae. Mol Cell Biol. 1994 Jul;14(7):4485-92. doi: 10.1128/mcb.14.7.4485-4492.1994. PMID:7516468 doi:http://dx.doi.org/10.1128/mcb.14.7.4485-4492.1994
- ↑ Feng Q, Moran JV, Kazazian HH Jr, Boeke JD. Human L1 retrotransposon encodes a conserved endonuclease required for retrotransposition. Cell. 1996 Nov 29;87(5):905-16. doi: 10.1016/s0092-8674(00)81997-2. PMID:8945517 doi:http://dx.doi.org/10.1016/s0092-8674(00)81997-2
- ↑ Sassaman DM, Dombroski BA, Moran JV, Kimberland ML, Naas TP, DeBerardinis RJ, Gabriel A, Swergold GD, Kazazian HH Jr. Many human L1 elements are capable of retrotransposition. Nat Genet. 1997 May;16(1):37-43. PMID:9140393 doi:http://dx.doi.org/10.1038/ng0597-37
- ↑ Jin W, Yu C, Zhang Y, Cao C, Xia T, Song G, Cai Z, Xue Y, Zhu B, Xu RM. Mechanism of DNA targeting by human LINE-1. Science. 2025 Oct 9;390(6769):eadu3433. PMID:41066570 doi:10.1126/science.adu3433
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