Fig. 2: Spliceosomal introns and intron-encoded homing endonucleases in mirusviruses.
a, The prevalence of spliceosomal introns and the intron-encoded homing endonucleases in four hallmark morphogenesis genes, across genomes from the major Mirusviricota putative orders. b, Structural features of the terminase gene from the genome ‘Mirus_G_0318’ of the putative order Okeanovirales that is highly abundant in parts of the Arctic Ocean. The terminase gene of this mirusvirus contains 20 spliceosomal introns and apparently undergoes trans-splicing of ATPase and nuclease domains that are encoded ~30 kb apart in the genome but form a contiguous transcript in the metatranscriptome. c, The 3D structure prediction of the terminase with the two terminase domains and the trans-splicing site. d, The metatranscriptomic signal (read recruitment for the forward and reverse strands) for the genome regions encoding the two trans-spliced domains of the terminase gene. The two genes (homing GIY–YIG endonuclease and MING-1) nested inside introns of the nuclease domain of the terminase are also shown. e, The predicted structure of MING-1 from d.
