Genomic Analysis of Bacteriophages SP6 and K1-5, an Estranged Subgroup of the T7 Supergroup

• Published in: Journal of molecular biology Vol. 335; no. 5; pp. 1151 - 1171
• Main Authors: Scholl, D., Kieleczawa, J., Kemp, P., Rush, J., Richardson, C.C., Merril, C., Adhya, S., Molineux, I.J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 30-01-2004
• Subjects: Bacteriophage T7 - genetics; Base Sequence; comparative genomics; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli - virology; Escherichia coli K1-5; Exons - genetics; Gene Expression Regulation; Genes, Regulator - genetics; Genome; genomic analysis; Introns - genetics; Molecular Sequence Data; Phage K1-5; Phage SP6; Podoviridae - genetics; Promoter Regions, Genetic - genetics; Salmonella Phages - genetics; Salmonella typhimurium; Salmonella typhimurium SP6; Sequence Homology, Nucleic Acid; T7 supergroup; Viral Tail Proteins - chemistry; Viral Tail Proteins - genetics; Virion - genetics; T7 supergroup; RNAP, RNA polymerase; Salmonella typhimurium SP6; Escherichia coli K1-5; genomic analysis; ORF, open reading frame; TR, terminal repeat; dsDNA, double-stranded DNA; comparative genomics
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/j.jmb.2003.11.035

We have determined the genome sequences of two closely related lytic bacteriophages, SP6 and K1-5, which infect
Salmonella typhimurium LT2 and
Escherichia coli serotypes K1 and K5, respectively. The genome organization of these phages is almost identical with the notable exception of the tail fiber genes that confer the different host specificities. The two phages have diverged extensively at the nucleotide level but they are still more closely related to each other than either is to any other phage currently characterized. The SP6 and K1-5 genomes contain, respectively, 43,769 bp and 44,385 bp, with 174 bp and 234 bp direct terminal repeats. About half of the 105 putative open reading frames in the two genomes combined show no significant similarity to database proteins with a known or predicted function that is obviously beneficial for growth of a bacteriophage. The overall genome organization of SP6 and K1-5 is comparable to that of the T7 group of phages, although the specific order of genes coding for DNA metabolism functions has not been conserved. Low levels of nucleotide similarity between genomes in the T7 and SP6 groups suggest that they diverged a long time ago but, on the basis of this conservation of genome organization, they are expected to have retained similar developmental strategies.