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Portal protein diversity and phage ecology
Article first published online: 31 JUL 2008
© 2008 The Authors. Journal compilation © 2008 Society for Applied Microbiology and Blackwell Publishing Ltd
Volume 10, Issue 10, pages 2810–2823, October 2008
How to Cite
Sullivan, M. B., Coleman, M. L., Quinlivan, V., Rosenkrantz, J. E., DeFrancesco, A. S., Tan, G., Fu, R., Lee, J. A., Waterbury, J. B., Bielawski, J. P. and Chisholm, S. W. (2008), Portal protein diversity and phage ecology. Environmental Microbiology, 10: 2810–2823. doi: 10.1111/j.1462-2920.2008.01702.x
- Issue published online: 10 SEP 2008
- Article first published online: 31 JUL 2008
- Received 10 February, 2008; accepted 7 June, 2008.
Vol. 13, Issue 10, 2832, Article first published online: 10 OCT 2011
Oceanic phages are critical components of the global ecosystem, where they play a role in microbial mortality and evolution. Our understanding of phage diversity is greatly limited by the lack of useful genetic diversity measures. Previous studies, focusing on myophages that infect the marine cyanobacterium Synechococcus, have used the coliphage T4 portal-protein-encoding homologue, gene 20 (g20), as a diversity marker. These studies revealed 10 sequence clusters, 9 oceanic and 1 freshwater, where only 3 contained cultured representatives. We sequenced g20 from 38 marine myophages isolated using a diversity of Synechococcus and Prochlorococcus hosts to see if any would fall into the clusters that lacked cultured representatives. On the contrary, all fell into the three clusters that already contained sequences from cultured phages. Further, there was no obvious relationship between host of isolation, or host range, and g20 sequence similarity. We next expanded our analyses to all available g20 sequences (769 sequences), which include PCR amplicons from wild uncultured phages, non-PCR amplified sequences identified in the Global Ocean Survey (GOS) metagenomic database, as well as sequences from cultured phages, to evaluate the relationship between g20 sequence clusters and habitat features from which the phage sequences were isolated. Even in this meta-data set, very few sequences fell into the sequence clusters without cultured representatives, suggesting that the latter are very rare, or sequencing artefacts. In contrast, sequences most similar to the culture-containing clusters, the freshwater cluster and two novel clusters, were more highly represented, with one particular culture-containing cluster representing the dominant g20 genotype in the unamplified GOS sequence data. Finally, while some g20 sequences were non-randomly distributed with respect to habitat, there were always numerous exceptions to general patterns, indicating that phage portal proteins are not good predictors of a phage's host or the habitat in which a particular phage may thrive.