Characterization of Pseudomonas chlororaphis myovirus 201φ{symbol}2-1 via genomic sequencing, mass spectrometry, and electron microscopy

Pseudomonas chlororaphis phage 201φ{symbol}2-1 is a relative of Pseudomonas aeruginosa myovirus φ{symbol}KZ. Phage 201φ{symbol}2-1 was examined by complete genomic sequencing (316,674 bp), by a comprehensive mass spectrometry survey of its virion proteins and by electron microscopy. Seventy-six proteins, of which at least 69 have homologues in φ{symbol}KZ, were identified by mass spectrometry. Eight proteins, in addition to the major head, tail sheath and tail tube proteins, are abundant in the virion. Electron microscopy of 201φ{symbol}2-1 revealed a multitude of long, fine fibers apparently decorating the tail sheath protein. Among the less abundant virion proteins are three homologues to RNA polymerase β or β′ subunits. Comparison between the genomes of 201φ{symbol}2-1 and φ{symbol}KZ revealed substantial conservation of the genome plan, and a large region with an especially high rate of gene replacement. The φ{symbol}KZ-like phages exhibited a two-fold higher rate of divergence than for T4-like phages or host genomes.