Adaptive evolution in LINE-1 retrotransposons

Stéphane Boissinot, Anthony V. Furano

Research output: Contribution to journalArticle

Abstract

We traced the sequence evolution of the active lineage of LINE-1 (L1) retrotransposons over the last ∼25 Myr of human evolution. Five major families (L1PA5, L1PA4, L1PA3B, L1PA2, and L1PA1) of elements have succeeded each other as a single lineage. We found that part of the first open-reading frame (ORFI) had a higher rate of nonsynonymous (amino acid replacement) substitution than synonymous substitution during the evolution of the ancestral L1PA5 through the L1PA3B families. This segment encodes the coiled coil region of the protein-protein interaction domain of the ORFI protein (ORFIp). Statistical analysis of these changes indicates that positive selection had been acting on this region. In contrast, the coiled coil segment hardly changed during the evolution of the L1PA3B to the present L1PA1 family. Therefore, selective pressure on the coiled coil segment has changed over time. We suggest that the fast rate of amino acid replacement in the coiled coil segment reflects the adaptation of L1 either to a changing genomic environment or to host repression factors. In contrast, the second open-reading frame and the nucleic acid-binding domain of the first open-reading frame are extremely well conserved, attesting to the strong purifying selection acting on these regions.

Original languageEnglish (US)
Pages (from-to)2186-2194
Number of pages9
JournalMolecular Biology and Evolution
Volume18
Issue number12
DOIs
StatePublished - 2001

Keywords

  • Human
  • L1/LINE-1
  • Positive selection
  • Retrotransposon

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Genetics

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