title: Genome organization and characterization of the virulent lactococcal phage 1358 and its similarities to Listeria phages.
abstract: Virulent phage 1358 is the reference member of a rare group of phages infecting Lactococcus lactis. Electron microscopy revealed a typical icosahedral capsid connected to one of the smallest noncontractile tails found in a lactococcal phage of the Siphoviridae family. Microbiological characterization identified a burst size of 72 virions released per infected host cell and a latent period of 90 min. The host range of phage 1358 was limited to 3 out of the 60 lactococcal strains tested. Moreover, this phage was insensitive to four Abi systems (AbiK, AbiQ, AbiT, and AbiV). The genome of phage 1358 consisted of a linear, double-stranded, 36,892-bp DNA molecule containing 43 open reading frames (ORFs). At least 14 ORFs coded for structural proteins, as identified by SDS-PAGE coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses. The genomic organization was similar to those of other siphophages. All genes were on the same coding strand and in the same orientation. This lactococcal phage was unique, however, in its 51.4% GC content, much higher than those of other phages infecting this low-GC Gram-positive host. A bias for GC-rich codons was also observed. Comparative analyses showed that several phage 1358 structural proteins shared similarity with two Listeria monocytogenes phages, P35 and P40. The possible origin and evolution of lactococcal phage 1358 is discussed.
authors.affiliation: Département de Biochimie et de Microbiologie, Faculté des Sciences et de Génie, Groupe de Recherche en Ecologie Buccale, Félix d'Hérelle Reference Center for Bacterial Viruses, Université Laval, Quebec City, Québec G1V 0A6, Canada.
authors.forename: Marie-Eve
authors.initials: ME
authors.lastname: Dupuis
authors.forename: Sylvain
authors.initials: S
authors.lastname: Moineau
mesh_terms: D001435:Bacteriophages / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology / Q000648:ultrastructure*; D001482:Base Composition; D002213:Capsid / Q000648:ultrastructure; D002853:Chromatography, Liquid; D004247:DNA / Q000235:genetics; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics*; D004591:Electrophoresis, Polyacrylamide Gel; D023061:Gene Order; D005814:Genes, Viral; D016679:Genome, Viral; D013294:Lactococcus lactis / Q000821:virology*; D013058:Mass Spectrometry; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D017422:Sequence Analysis, DNA; D014764:Viral Proteins / Q000032:analysis; D014771:Virion / Q000648:ultrastructure
chemical_list: D004279:DNA, Viral; D014764:Viral Proteins; D004247:DNA