Abstract
L1 LINE retrotransposons play a key role in the formation and sustainable evolution of mammalian genomes. In particular, L1 retrotransposons, which occupy approximately 20% of genomic DNA, transduce their 3′-flanking sequences to new genomic loci and create pseudogenes via reverse transcription of different types of cellular RNAs. Recently, we discovered several families of chimeric pseudogenes in mammalian genomes consisting of fused copies of various cellular transcripts. Characteristic features of such chimeric inserts are indicative of the involvement of L1 enzymatic machinery in their formation. A detailed sequence analysis showed that the 5′-terminal parts of the chimeras were copies of nuclear RNAs, whereas the 3′-terminal parts were formed on the templates of transcripts that have a cytoplasmic location. A mechanism of chimera formation, including a switch of templates during RNA reverse transcription catalyzed by L1 reverse transcriptase, is proposed. The presence in the mammalian genome of not only “double” but also “triple” chimeric retrogenes indicates that not only a single but also a double template switch may occur during L1-catalyzed reverse transcription. Some of the chimeras identified were transcriptionally active, which allowed us to regard the discovered phenomenon as a new mechanism of gene formation by “shuffling” preexisting transcribed sequences. This mechanism currently functions in mammalian genomes; it appeared at least 75 million years ago and is evolutionarily conserved.
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Translated from Molekulyarnaya Biologiya, Vol. 39, No. 3, 2005, pp. 364–373.
Original Russian Text Copyright © 2005 by Gogvadze, Buzdin.
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Gogvadze, E.V., Buzdin, A.A. A New Mechanism of Retrogene Formation in Mammalian Genomes: In Vivo Recombination during RNA Reverse Transcription. Mol Biol 39, 321–330 (2005). https://doi.org/10.1007/s11008-005-0045-5
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DOI: https://doi.org/10.1007/s11008-005-0045-5