Virophages and retrotransposons colonize the genomes of a heterotrophic flagellate

eLife

Matthias G Fischer¹  Sarah Duponchel¹  Alexa Weinmann¹  Thomas Hackl¹  Karina Barenhoff¹ 

[1] Max Planck Institute for Medical Research, Department of Biomolecular Mechanisms, Heidelberg, Germany;

关键词: Cafeteria burkhardae;    virophage;    retrotransposon;    protist;    endogenous viral element;    antiviral defense;    Viruses;    Other;   

DOI  :  10.7554/eLife.72674

来源: eLife Sciences Publications, Ltd

【 摘 要 】

Virophages can parasitize giant DNA viruses and may provide adaptive anti-giant virus defense in unicellular eukaryotes. Under laboratory conditions, the virophage mavirus integrates into the nuclear genome of the marine flagellate Cafeteria burkhardae and reactivates upon superinfection with the giant virus CroV. In natural systems, however, the prevalence and diversity of host-virophage associations has not been systematically explored. Here, we report dozens of integrated virophages in four globally sampled C. burkhardae strains that constitute up to 2% of their host genomes. These endogenous mavirus-like elements (EMALEs) separated into eight types based on GC-content, nucleotide similarity, and coding potential and carried diverse promoter motifs implicating interactions with different giant viruses. Between host strains, some EMALE insertion loci were conserved indicating ancient integration events, whereas the majority of insertion sites were unique to a given host strain suggesting that EMALEs are active and mobile. Furthermore, we uncovered a unique association between EMALEs and a group of tyrosine recombinase retrotransposons, revealing yet another layer of parasitism in this nested microbial system. Our findings show that virophages are widespread and dynamic in wild Cafeteria populations, supporting their potential role in antiviral defense in protists.

【 授权许可】

CC BY