The genome of S-PM2, a "photosynthetic" T4-type bacteriophage that infects marine Synechococcus strains.
Bacteriophage S-PM2 infects several strains of the abundant and ecologically important marine cyanobacterium Synechococcus. A large lytic phage with an isometric icosahedral head, S-PM2 has a contractile tail and by this criterion is classified as a myovirus (1). The linear, circularly permuted, 196,280-bp double-stranded DNA genome of S-PM2 contains 37.8% G+C residues. It encodes 239 open reading frames (ORFs) and 25 tRNAs. Of these ORFs, 19 appear to encode proteins associated with the cell envelope, including a putative S-layer-associated protein. Twenty additional S-PM2 ORFs have homologues in the genomes of their cyanobacterial hosts. There is a group I self-splicing intron within the gene encoding the D1 protein. A total of 40 ORFs, organized into discrete clusters, encode homologues of T4 proteins involved in virion morphogenesis, nucleotide metabolism, gene regulation, and DNA replication and repair. The S-PM2 genome encodes a few surprisingly large (e.g., 3,779 amino acids) ORFs of unknown function. Our analysis of the S-PM2 genome suggests that many of the unknown S-PM2 functions may be involved in the adaptation of the metabolism of the host cell to the requirements of phage infection. This hypothesis originates from the identification of multiple phage-mediated modifications of the host's photosynthetic apparatus that appear to be essential for maintaining energy production during the lytic cycle.
Mann
Nicholas H
NH
Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK. N.H.Mann@warwick.ac.uk
Clokie
Martha R J
MR
Millard
Andrew
A
Cook
Annabel
A
Wilson
William H
WH
Wheatley
Peter J
PJ
Letarov
Andrey
A
Krisch
H M
HM
D001435:Bacteriophages / Q000235:genetics*; D001482:Base Composition; D018387:Codon, Initiator; D004260:DNA Repair; D004261:DNA Replication; D004279:DNA, Viral / Q000737:chemistry / Q000302:isolation & purification; D016679:Genome, Viral; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D012045:Regulatory Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA; D046940:Synechococcus / Q000821:virology*; D014759:Viral Envelope Proteins / Q000235:genetics; D014771:Virion / Q000235:genetics
D018387:Codon, Initiator; D004279:DNA, Viral; D014759:Viral Envelope Proteins