Figure 2.

Characterization of hyperthermophilic pleomorphic viruses and their VP4-like membrane fusion proteins; (A) alignment of complete or nearly-complete genomes of pleomorphic viruses originating from marine deep-sea hydrothermal vents; ORFs are depicted by arrows that indicate the direction of transcription; functional annotations are depicted above the corresponding ORFs; homologous genes are shown using the same colors and are connected by shading in grayscale, with intensity reflecting the amino acid sequence identity; HJR, Holliday junction resolvase; NT, nucleotidyltransferase; PH, pleckstrin homology domain; PIN, PIN domain protein; RHH, ribbon-helix–helix protein; TGM, transglutaminase; wHTH, winged helix-turn-helix domain; Zn finger, zinc finger domain-containing protein; (B) geographical distribution of all hyperthermophilic pleomorphic viruses retrieved in this study; (C) maximum-likelihood analysis of VP4-like fusogens; clades of VP4 homologs encoded by viruses associated with different archaeal lineages are indicated with different colors; the scale bar represents the number of substitutions per site; circles at nodes indicate bootstrap support >90%; the complete version of the tree can be found in Fig. S6; (D) number of glycosylation sites (N-X-S/T, where X is any amino acid except proline) in VP4-like fusogens of pleomorphic viruses infecting Archaeoglobi, Halobacteria, Methanonatronarchaeia, and Methanomassiliicoccales hosts; stars indicate the significance levels based on the unpaired t-test; n.s., not significant; the P values are <.0001, <.0001, .2996 from left to right.