†Present address: Pittsburgh Bacteriophage Institute, University of Pittsburgh, Pittsburgh, PA 15260, USA.
A freshwater cyanophage whose genome indicates close relationships to photosynthetic marine cyanomyophages
Article first published online: 23 MAY 2011
© 2011 Society for Applied Microbiology and Blackwell Publishing Ltd
Thematic Issue: Pseudomonas
Volume 13, Issue 7, pages 1858–1874, July 2011
How to Cite
Dreher, T. W., Brown, N., Bozarth, C. S., Schwartz, A. D., Riscoe, E., Thrash, C., Bennett, S. E., Tzeng, S.-C. and Maier, C. S. (2011), A freshwater cyanophage whose genome indicates close relationships to photosynthetic marine cyanomyophages. Environmental Microbiology, 13: 1858–1874. doi: 10.1111/j.1462-2920.2011.02502.x
- Issue published online: 3 JUL 2011
- Article first published online: 23 MAY 2011
- Received 21 November, 2010; accepted 1 April, 2011.
Bacteriophage S-CRM01 has been isolated from a freshwater strain of Synechococcus and shown to be present in the upper Klamath River valley in northern California and Oregon. The genome of this lytic T4-like phage has a 178 563 bp circular genetic map with 297 predicted protein-coding genes and 33 tRNA genes that represent all 20-amino-acid specificities. Analyses based on gene sequence and gene content indicate a close phylogenetic relationship to the ‘photosynthetic’ marine cyanomyophages infecting Synechococcus and Prochlorococcus. Such relatedness suggests that freshwater and marine phages can draw on a common gene pool. The genome can be considered as being comprised of three regions. Region 1 is populated predominantly with structural genes, recognized as such by homology to other T4-like phages and by identification in a proteomic analysis of purified virions. Region 2 contains most of the genes with roles in replication, recombination, nucleotide metabolism and regulation of gene expression, as well as 5 of the 6 signature genes of the photosynthetic cyanomyophages (hli03, hsp20, mazG, phoH and psbA; cobS is present in Region 3). Much of Regions 1 and 2 are syntenic with marine cyanomyophage genomes, except that a segment encompassing Region 2 is inverted. Region 3 contains a high proportion (85%) of genes that are unique to S-CRM01, as well as most of the tRNA genes. Regions 1 and 2 contain many predicted late promoters, with a combination of CTAAATA and ATAAATA core sequences. Two predicted genes that are unusual in phage genomes are homologues of cellular spoT and nusG.