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bioRxiv · 10.1101/2024.10.01.616040

LINE-1 ribonucleoprotein complexes bind DNA to enable nuclear entry during mitosis

Zernia, S.·Ettefa, F.·Sil, S.·Koeman, C.·Deplazes-Lauber, J.·Freitag, M.·Holt, L. J.·Stigler, J.
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Abstract

Long Interspersed Nuclear Element-1 (LINE-1) is an autonomous retrotransposon that makes up a significant portion of the human genome, contributing to genetic diversity and genome evolution. LINE-1 encodes two proteins, ORF1p and ORF2p, both essential for successful retrotransposition. ORF2p has endonuclease and reverse transcription activity, while ORF1p binds RNA. Many copies of ORF1p assemble onto the LINE-1 RNA to form a ribonucleoprotein complex (RNP). However, the functional role of RNPs in the LINE-1 life cycle is unclear. Using reconstitution assays on DNA curtains, we show that L1 RNPs gain DNA binding activity only when RNA is super-saturated with ORF1p. In cells, L1 RNPs bind to chromosomes during mitosis. Mutational analysis reveals that DNA binding is crucial for nuclear entry and LINE-1 retrotransposition activity. Thus, a key function of ORF1p is to form an RNP that gains access to the genome through DNA binding upon nuclear envelope breakdown.

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Zernia, S., Ettefa, F., Sil, S., Koeman, C., Deplazes-Lauber, J., Freitag, M., Holt, L. J., Stigler, J.. 2024-10-02. LINE-1 ribonucleoprotein complexes bind DNA to enable nuclear entry during mitosis. https://doi.org/10.1101/2024.10.01.616040

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