Genomes of marine cyanopodoviruses reveal multiple origins of diversity.

TitleGenomes of marine cyanopodoviruses reveal multiple origins of diversity.
Publication TypeJournal Article
Year of Publication2013
AuthorsLabrie, SJ, Frois-Moniz, K, Osburne, MS, Kelly, L, Roggensack, SE, Sullivan, MB, Gearin, G, Zeng, Q, Fitzgerald, M, Henn, MR, Chisholm, SW
JournalEnviron Microbiol
Date Published2013 May
KeywordsCyanobacteria, DNA-Directed DNA Polymerase, Genetic Variation, Genome, Viral, Genomic Islands, Metagenomics, Oceans and Seas, Phylogeny, Podoviridae, Prochlorococcus, Seawater, Sequence Alignment, Synechococcus

The marine cyanobacteria Prochlorococcus and Synechococcus are highly abundant in the global oceans, as are the cyanophage with which they co-evolve. While genomic analyses have been relatively extensive for cyanomyoviruses, only three cyanopodoviruses isolated on marine cyanobacteria have been sequenced. Here we present nine new cyanopodovirus genomes, and analyse them in the context of the broader group. The genomes range from 42.2 to 47.7 kb, with G+C contents consistent with those of their hosts. They share 12 core genes, and the pan-genome is not close to being fully sampled. The genomes contain three variable island regions, with the most hypervariable genes concentrated at one end of the genome. Concatenated core-gene phylogeny clusters all but one of the phage into three distinct groups (MPP-A and two discrete clades within MPP-B). The outlier, P-RSP2, has the smallest genome and lacks RNA polymerase, a hallmark of the Autographivirinae subfamily. The phage in group MPP-B contain photosynthesis and carbon metabolism associated genes, while group MPP-A and the outlier P-RSP2 do not, suggesting different constraints on their lytic cycles. Four of the phage encode integrases and three have a host integration signature. Metagenomic analyses reveal that cyanopodoviruses may be more abundant in the oceans than previously thought.

Alternate JournalEnviron. Microbiol.
PubMed ID23320838