Putative major capsid proteins of Polintons, Tlr elements and the PgVV virophage. A. Maximum likelihood phylogenetic analysis of the putative DJR MCPs. Numbers at the branch points represent SH-like local support values. B. Conservation of the genes for the genome packaging ATPase (red boxes), penton protein (green boxes), and adenoviral protease (blue boxes) in Polintons containing intact MCP genes. The presence of the corresponding split genes is indicated with lighter shading, and absence of identifiable genes is shown with empty boxes. The full information on the gene presence-absence pattern is provided in Additional file 1: Table S1. C. Structural models of the Polinton and Tlr MCP genes along with the X-ray structure of the VP54 of PBCV-1 (PDB ID: 1M3Y). The models are colored according to the secondary structure elements: green, beta-strands; red, alpha-helixes).