title: DNA Packaging Specificity of Bacteriophage N15 with an Excursion into the Genetics of a Cohesive End Mismatch.
abstract: During DNA replication by the λ-like bacteriophages, immature concatemeric DNA is produced by rolling circle replication. The concatemers are processed into mature chromosomes with cohesive ends, and packaged into prohead shells, during virion assembly. Cohesive ends are generated by the viral enzyme terminase, which introduces staggered nicks at cos, an approx. 200 bp-long sequence containing subsites cosQ, cosN and cosB. Interactions of cos subsites of immature concatemeric DNA with terminase orchestrate DNA processing and packaging. To initiate DNA packaging, terminase interacts with cosB and nicks cosN. The cohesive ends of N15 DNA differ from those of λ at 2/12 positions. Genetic experiments show that phages with chromosomes containing mismatched cohesive ends are functional. In at least some infections, the cohesive end mismatch persists through cyclization and replication, so that progeny phages of both allelic types are produced in the infected cell. N15 possesses an asymmetric packaging specificity: N15 DNA is not packaged by phages λ or 21, but surprisingly, N15-specific terminase packages λ DNA. Implications for genetic interactions among λ-like bacteriophages are discussed.
authors.affiliation: Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, 52242, United States of America.
authors.forename: Michael
authors.initials: M
authors.lastname: Feiss
authors.affiliation: Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, 52242, United States of America.
authors.forename: Jea
authors.initials: J
authors.lastname: Young Min
authors.affiliation: Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, 52242, United States of America.
authors.forename: Sawsan
authors.initials: S
authors.lastname: Sultana
authors.affiliation: Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, 52242, United States of America.
authors.forename: Priyal
authors.initials: P
authors.lastname: Patel
authors.affiliation: Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, 52242, United States of America.
authors.forename: Jean
authors.initials: J
authors.lastname: Sippy
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics*; D001665:Binding Sites / Q000235:genetics; D042003:DNA Packaging; D004261:DNA Replication; D004279:DNA, Viral / Q000235:genetics*; D019065:Virus Assembly / Q000235:genetics*
chemical_list: D004279:DNA, Viral