Figure 4.

HEG-islands bracket regions of essential gene cargo in phages. (A–C) Gene neighborhoods are shown that contain HEGs in proximity to genes involved in phage tail morphogenesis (A), phage genome replication (B), or phage capsid morphogenesis (C). Examples of greater than 60% nucleotide identity between the phages are indicated by black-shaded parallelograms between the gene graphs. Gene fragments predicted to splice are outlined in bold, with gray dashed lines connecting the exons. Genes are colored according to the HEG nuclease domain and labeled according to the predicted gene function, as determined by HHsearch domain prediction. Domain key: terL = large terminase, DNA Pol = DNA polymerase, nrdA/B/D = ribonucleoside-triphosphate reductase, MCP = major coat subunit, Prot = scaffold protease, TMP = tape measure protein, H = RNase H.