Mobile introns shape the genetic diversity of their host genes

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Title: Mobile introns shape the genetic diversity of their host genes
Authors: Repar, J
Warnecke, T
Item Type: Journal Article
Abstract: Self-splicing introns populate several highly conserved protein-coding genes in fungal and plant mitochondria. In fungi, many of these introns have retained their ability to spread to intron-free target sites, often assisted by intron-encoded endonucleases that initiate the homing process. Here, leveraging population genomic data from Saccharomyces cerevisiae, Schizosaccharomyces pombe, and Lachancea kluyveri, we expose non-random patterns of genetic diversity in exons that border self-splicing introns. In particular, we show that, in all three species, the density of single nucleotide polymorphisms increases as one approaches a mobile intron. Through multiple lines of evidence we rule out relaxed purifying selection as the cause of uneven nucleotide diversity. Instead, our findings implicate intron mobility as a direct driver of host gene diversity. We discuss two mechanistic scenarios that are consistent with the data: either endonuclease activity and subsequent error-prone repair have left a mutational footprint on the insertion environment of mobile introns or non-random patterns of genetic diversity are caused by exonic co-conversion, which occurs when introns spread to empty target sites via homologous recombination. Importantly, however, we show that exonic co-conversion can only explain diversity gradients near intron-exon boundaries if the conversion template comes from outside the population. In other words, there must be pervasive and ongoing horizontal gene transfer of self-splicing introns into extant fungal populations.
Issue Date: 30-Mar-2017
Date of Acceptance: 7-Feb-2017
ISSN: 1943-2631
Publisher: Genetics Society of America
Start Page: 1641
End Page: 1648
Journal / Book Title: Genetics
Volume: 205
Issue: 4
Copyright Statement: Copyright © 2017 Repar and Warnecke Available freely online through the author-supported open access option. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Sponsor/Funder: Imperial College London
Medical Research Council
Funder's Grant Number: Junior Research Fellowship
Keywords: gene conversion
genetic diversity
homing endonuclease
self-splicing introns
Developmental Biology
0604 Genetics
Publication Status: Published
Appears in Collections:Clinical Sciences
Molecular Sciences
Faculty of Medicine

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