Researchers from Nanjing Normal University have made an important breakthrough on the co-option of selfish element genes in eukaryotes. The article, entitled “Unearthing LTR retrotransposon gag genes co-opted in the deep evolution of eukaryotes”, was published in Molecular Biology and Evolution with graduate student Jianhua Wang as the first author.   

LTR retrotransposons, a major type of selfish elements, comprise a major component of the genomes of eukaryotes. On occasion, retrotransposon genes can be recruited by their hosts for diverse functions, a process formally referred to as co-option. However, a comprehensive picture of LTR retrotransposon gag gene co-option in eukaryotes is still lacking. The researchers used a comparative genomics approach to systemically unearth co-option of retrotransposon gag genes above the family level of taxonomy in 2,011 eukaryotes. These co-option events occurred during the deep evolution of eukaryotes. They identified a total of 14 independent gag gene co-option events across more than 740 eukaryote families, eight of which have not been reported previously. Among these retrotransposon gag gene co-option events, nine, four, and one involve gag genes of Ty3/Gypsy, Ty1/Copia, and Bel-Pao retrotransposons, respectively. Seven, four, and three co-option events occurred in animals, plants, and fungi, respectively. Both selective pressure and gene expression analyses further support that these co-opted gag genes might perform diverse cellular functions in their hosts, and several co-opted gag genes might be subject to positive selection. The article provides a comprehensive picture of LTR retrotransposon gag gene co-option events that occurred during the deep evolution of eukaryotes, and suggests paucity of LTR retrotransposon gag gene co-option during the deep evolution of eukaryotes.   

Support for the project was provided by the National Natural Science Foundation of China and the Priority Academic Program Development of Jiangsu Province.