PY54, a linear plasmid prophage of Yersinia enterocolitica with covalently closed ends

Abstract

SummaryPY54 is a temperate phage isolated from Yersinia enterocolitica . Lysogenic Yersinia strains harbour the PY54 prophage as a plasmid (pY54). The plasmid has the same size (46 kb) as the PY54 genome isolated from phage particles. By electron microscopy, restriction analysis and DNA sequencing, it was demonstrated that the phage and the plasmid DNAs are linear, circularly permuted molecules. Unusually for phages of Gram-negative bacteria, the phage genome has 3 ¢ ¢ ¢ ¢ -protruding ends. The linear plasmid pY54 has covalently closed ends forming telomere-like hairpins. The equivalent DNA sequence of the phage genome is a 42 bp perfect palindrome. Downstream from the palindrome, an open reading frame (ORF) was identified that revealed strong DNA homology to the telN gene of Escherichia coli phage N15 encoding a protelomerase. Similar to PY54, the N15 prophage is a linear plasmid with telomeres. The N15 protelomerase has cleaving/joining activity generating the telomeres by processing a 56 bp palindrome (telomere resolution site telRL ). To study the activity of the PY54 protein, the telN -like gene was cloned and expressed in E. coli . A 77 kDa protein was obtained and partially purified. The protein was found to process recombinant plasmids containing the 42 bp palindrome. Telomere resolution of plasmids under in vivo conditions was also investigated in Yersinia infected with PY54. Processing required a plasmid containing the palindrome as well as adjacent DNA sequences from the phage including an additional inverted repeat. Regions on the phage genome important for plasmid maintenance were defined by the construction of linear and circular miniplasmid derivatives of pY54, of which the smallest miniplasmid comprises a 4.5 kb DNA fragment of the plasmid prophage.

Yersiniophage ϕR1-37 is a tailed bacteriophage having a 270 kb DNA genome with thymidine replaced by deoxyuridine

“…Likewise, Yersinia pestis phage wA1122 was recently found to be a close relative of T7 (Garcia et al, 2003a). Bacteriophage PY54 is a temperate phage isolated from Y. enterocolitica O : 5 that maintains its lysogeny by replicating as a linear plasmid with covalently closed ends (Hertwig et al, 2003a, b). The GenBank/EMBL/DDBJ accession numbers for the sequences reported in this paper are AJ972879 and AJ972880.…”

Two novel temperate bacteriophages co-existing in Aeromonas sp. ARM81 – characterization of their genomes, proteomes and DNA methyltransferases

“…Apart from 'a prototype' -the enterobacteria phage N15, which was isolated in 1964 -only six other phages are known to lysogenize their hosts as linear telomere plasmids (Ravin, 2015). They are the siphoviruses FKO2 of Klebsiella oxytoca (Casjens et al, 2004) and PY54 of Yersinia enterocolitica (Hertwig et al, 2003), and the myoviruses of marine bacteria: VP882, Vp58.5 and vB_VpaM_-MAR of Vibrio parahaemolyticus (Lan et al, 2009;Zabala et al, 2009;Alanis Villa et al, 2012), and FHAP-1 of Halomonas aquamarina (Mobberley et al, 2008). All of them encode a hallmark protein called protelomerase, along with plasmid partitioning proteins ParA and ParB, required for this type of lysogeny.…”

Production of Double-stranded DNA Ministrings

“…This may be attributed to the amount of time required for Tel expression and activity. The originating prophage PY54 encoding Tel protelomerase normally infects Yersinia, which optimally grows around 28 °C 12 , indicating that 30 °C may also be more optimal for Tel activity.…”