title: A novel lysis system in PM2, a lipid-containing marine double-stranded DNA bacteriophage.
abstract: In this study we investigated the lysis system of the lipid-containing double-stranded DNA bacteriophage PM2 infecting Gram-negative marine Pseudoalteromonas species. We analysed wt and lysis-deficient phage-induced changes in the host physiology and ascribed functions to two PM2 gene products (gp) involved in lysis. We show that bacteriophage PM2 uses a novel system to disrupt the infected cell. The novelty is based on the following findings: (i) gp k is needed for the permeabilization of the cytoplasmic membrane and appears to play the role of a typical holin. However, its unique primary structure [53 aa, 1 transmembrane domain (TMD)] places it into a new class of holins. (ii) We have proposed that, unlike other bacteriophages studied, PM2 relies on lytic factors of the cellular origin for digestion of the peptidoglycan. (iii) gp l (51 aa, no TMDs) is needed for disruption of the outer membrane, which is highly rigidified by the divalent cations abundant in the marine environment. The gp l has no precedent in other phage lytic systems studied so far. However, the presence of open reading frame l-like genes in genomes of other bacterial viruses suggests that the same system might be used by other phages and is not unique to PM2.
authors.affiliation: Department of Biological and Environmental Sciences and Institute of Biotechnology, Biocenter 2, PO Box 56 (Viikinkaari 5), 00014 University of Helsinki, Finland.
authors.forename: Mart
authors.initials: M
authors.lastname: Krupovic
authors.forename: Rimantas
authors.initials: R
authors.lastname: Daugelavicius
authors.forename: Dennis H
authors.initials: DH
authors.lastname: Bamford
mesh_terms: D000595:Amino Acid Sequence; D001433:Bacteriolysis; D019240:Corticoviridae / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D004247:DNA / Q000235:genetics; D008055:Lipids / Q000032:analysis*; D008242:Lysogeny; D008969:Molecular Sequence Data; D031161:Pseudoalteromonas / Q000502:physiology* / Q000821:virology*; D012623:Seawater / Q000382:microbiology / Q000821:virology*; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D008055:Lipids; D014764:Viral Proteins; D004247:DNA