title: The Shiga-toxin VT2-encoding bacteriophage varphi297 integrates at a distinct position in the Escherichia coli genome.
abstract: The plaque-forming VT2-encoding lambdoid bacteriophage varphi297 was isolated from a Belgian clinical Escherichia coli O157:H7 isolate. PCR walking, starting from the int gene of phage varphi297, demonstrated that the varphi297 prophage integrated in the yecE gene of a lysogenic E. coli K12 strain. This integration site, in E. coli K12 and in the original clinical O157:H7 isolate, was confirmed by PCR using primers flanking this site. The excisionase protein of phage varphi297 is identical to the excisionase of VT1-encoding phage VT1-Sakai, while the integrases, which are 82% identical, show significant sequence divergence in the central and C-terminal region. This can explain the different integration sites of both prophages. The activity of the integrase was proven by its ability to mediate the integration of a suicide plasmid, carrying the attachment site of varphi297, at the appropriate position in the E. coli chromosome.
authors.affiliation: Laboratorium Genetische Virologie, Vrije Universiteit Brussel, Paardenstraat 65, B-1640 Sint-Genesius-Rode, Belgium. hdegreve@vub.ac.be
authors.forename: Henri
authors.initials: H
authors.lastname: De Greve
authors.forename: Cao
authors.initials: C
authors.lastname: Qizhi
authors.forename: Francine
authors.initials: F
authors.lastname: Deboeck
authors.forename: Jean Pierre
authors.initials: JP
authors.lastname: Hernalsteens
mesh_terms: D000595:Amino Acid Sequence; D001435:Bacteriophages / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D004254:DNA Nucleotidyltransferases / Q000235:genetics; D019453:Escherichia coli O157 / Q000235:genetics* / Q000302:isolation & purification / Q000821:virology; D019143:Evolution, Molecular; D006801:Humans; D019426:Integrases / Q000235:genetics; D008242:Lysogeny; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D039002:Prophages / Q000235:genetics; D016415:Sequence Alignment; D022641:Shiga Toxin 2 / Q000737:chemistry / Q000235:genetics*; D014764:Viral Proteins; D016662:Virus Integration
chemical_list: D022641:Shiga Toxin 2; D014764:Viral Proteins; D004254:DNA Nucleotidyltransferases; D019426:Integrases; C063911:excisionase