Systems biology of phage proteins and new dimensions of the virus world discovered through metagenomics

Wednesday, October 26, 2011 — Poster Session IV
2:00 p.m. – 4:00 p.m.	Natcher Conference Center	NLM	VIROL/MICRO-12

Authors

• DM Kristensen
• AR Mushegian
• EV Koonin

Abstract

Phages are extremely active players in the global ecosystem, as well as the most abundant organisms on planet Earth, but much remains unknown about how these viruses function in their natural environments. Advances in full-genome sequencing technologies have generated a large collection of hundreds of genomes, which allows deep insight into their genetic evolution, and metagenomics technologies seem to promise more rewarding glimpses into their lifecycles and community structures. Recently we developed an automated approach to assemble a collection of orthologous gene clusters of phages (Phage Orthologous Groups, or POGs). Using this approach, we found that more than half of the POGs have no or very few evolutionary connections to their hosts, indicating that phages combine the ability to share and transduce host genes with the ability to maintain a large fraction of unique, phage-specific genes. Such genes are useful for targeted research strategies, including diagnostic indicators and fundamental units of systems biology studies. We employed this set further to probe the composition of several oceanic metagenome samples, where we found that the gene repertoire of the marine DNA virome differs dramatically from that of known bacteriophages, and may instead represent cellular gene transfer agents (GTAs) rather than true viruses.

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