Comparative Genomics of Cluster O Mycobacteriophages

Mycobacteriophages – viruses of mycobacterial hosts – are genetically diverse but morphologicallyare all classified in the Caudovirales with double-stranded DNA and tails. We describehere a group of five closely related mycobacteriophages – Corndog, Catdawg,Dylan, Firecracker, and YungJamal – designated as Cluster O with long flexible tails butwith unusual prolate capsids. Proteomic analysis of phage Corndog particles, Catdawg particles,and Corndog-infected cells confirms expression of half of the predicted gene productsand indicates a non-canonical mechanism for translation of the Corndog tape measureprotein. Bioinformatic analysis identifies 8–9 strongly predicted SigA promoters and all fiveCluster O genomes contain more than 30 copies of a 17 bp repeat sequence with dyad symmetrylocated throughout the genomes. Comparison of the Cluster O phages provides insightsinto phage genome evolution including the processes of gene flux by horizontalgenetic exchange