Tail structure region of VpV262.

Focused searches identified additional homologues between VpV262 and SIO1.  It was not possible to specifically establish homology to particular T7 proteins.  However, the pattern of matching in itself reveals the likely identity of the major tail proteins.

• T7-like viruses have a very large internal virion protein that extends upon infection to become a longer tail.  It is usually poorly conserved except for recognition domains for the bacteria at the C terminus.  VpV262 orfU by size alone is probably a distant homologue of this protein.
• T7 (and all phages) have tail fibers that extend and have recognition domains for the bacteria at their C termini.  These proteins are notoriously mosaic in their structure, with the C termini often exchanged even between closely related viruses.  This presumably reflects the coadaptive struggle with the host.  VpV262 orf N fits this pattern.