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Environ Microbiol. 2011 Jul;13(7):1858-74. doi: 10.1111/j.1462-2920.2011.02502.x. Epub 2011 May 23.

A freshwater cyanophage whose genome indicates close relationships to photosynthetic marine cyanomyophages.

Author information

1
Department of Microbiology, Oregon State University, Corvallis, Oregon 97331, USA. theo.dreher@oregonstate.edu

Abstract

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.

PMID:
21605306
PMCID:
PMC4185292
DOI:
10.1111/j.1462-2920.2011.02502.x
[Indexed for MEDLINE]
Free PMC Article
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