Complete genomic sequence of the virulent Salmonella bacteriophage SP6.
We report the complete genome sequence of enterobacteriophage SP6, which infects Salmonella enterica serovar Typhimurium. The genome contains 43,769 bp, including a 174-bp direct terminal repeat. The gene content and organization clearly place SP6 in the coliphage T7 group of phages, but there is approximately 5 kb at the right end of the genome that is not present in other members of the group, and the homologues of T7 genes 1.3 through 3 appear to have undergone an unusual reorganization. Sequence analysis identified 10 putative promoters for the SP6-encoded RNA polymerase and seven putative rho-independent terminators. The terminator following the gene encoding the major capsid subunit has a termination efficiency of about 50% with the SP6-encoded RNA polymerase. Phylogenetic analysis of phages related to SP6 provided clear evidence for horizontal exchange of sequences in the ancestry of these phages and clearly demarcated exchange boundaries; one of the recombination joints lies within the coding region for a phage exonuclease. Bioinformatic analysis of the SP6 sequence strongly suggested that DNA replication occurs in large part through a bidirectional mechanism, possibly with circular intermediates.
Dobbins
Aleisha T
AT
Department of Biochemistry and Molecular Biology, Howard University College of Medicine, Washington, DC 20059, USA.
George
Matthew
M
Basham
Daryl A
DA
Ford
Michael E
ME
Houtz
Jennifer M
JM
Pedulla
Marisa L
ML
Lawrence
Jeffrey G
JG
Hatfull
Graham F
GF
Hendrix
Roger W
RW
D000595:Amino Acid Sequence; D001483:Base Sequence; D004261:DNA Replication; D015967:Gene Expression Regulation, Viral; D016679:Genome, Viral; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D011401:Promoter Regions, Genetic / Q000235:genetics; D012483:Salmonella Phages / Q000235:genetics*; D012486:Salmonella typhimurium / Q000821:virology*; D017422:Sequence Analysis, DNA; D013728:Terminator Regions, Genetic / Q000235:genetics; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics
D014764:Viral Proteins