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Penetration of membrane-containing double-stranded-DNA bacteriophage PM2 into Pseudoalteromonas hosts.

ABSTRACT: The icosahedral bacteriophage PM2 has a circular double-stranded DNA (dsDNA) genome and an internal lipid membrane. It is the only representative of the Corticoviridae family. How the circular supercoiled genome residing inside the viral membrane is translocated into the gram-negative marine Pseudoalteromonas host has been an intriguing question. Here we demonstrate that after binding of the virus to an abundant cell surface receptor, the protein coat is most probably dissociated. During the infection process, the host cell outer membrane becomes transiently permeable to lipophilic gramicidin D molecules proposing fusion with the viral membrane. One of the components of the internal viral lipid core particle is the integral membrane protein P7, with muralytic activity that apparently aids the process of peptidoglycan penetration. Entry of the virion also causes a limited depolarization of the cytoplasmic membrane. These phenomena differ considerably from those observed in the entry process of bacteriophage PRD1, a dsDNA virus, which uses its internal membrane to make a cell envelope-penetrating tubular structure.

SUBMITTER: Kivela HM

PROVIDER: S-EPMC490941 | biostudies-literature | 2004 Aug

REPOSITORIES: biostudies-literature

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Penetration of membrane-containing double-stranded-DNA bacteriophage PM2 into Pseudoalteromonas hosts.

Kivelä Hanna M HM Daugelavicius Rimantas R Hankkio Riina H RH Bamford Jaana K H JK Bamford Dennis H DH

Journal of bacteriology 20040801 16

The icosahedral bacteriophage PM2 has a circular double-stranded DNA (dsDNA) genome and an internal lipid membrane. It is the only representative of the Corticoviridae family. How the circular supercoiled genome residing inside the viral membrane is translocated into the gram-negative marine Pseudoalteromonas host has been an intriguing question. Here we demonstrate that after binding of the virus to an abundant cell surface receptor, the protein coat is most probably dissociated. During the inf ...[more]

PMID: 15292135

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Project description:The tailed double-stranded DNA (dsDNA) bacteriophage 29 packages its 19.3-kbp genome into a preassembled procapsid structure by using a transiently assembled phage-encoded molecular motor. This process is remarkable considering that compaction of DNA to near-crystalline densities within the confined space of the capsid requires that the packaging motor work against significant entropic, enthalpic, and DNA-bending energies. The motor consists of three phage-encoded components: the dodecameric connector protein gp10, an oligomeric RNA molecule known as the prohead RNA (pRNA), and the homomeric ring ATPase gp16. Although atomic resolution structures of the connector and different pRNA subdomains have been determined, the mechanism of self-assembly and the resulting stoichiometry of the various motor components on the phage capsid have been the subject of considerable controversy. Here a subnanometer asymmetric cryoelectron microscopy (cryo-EM) reconstruction of a connector-pRNA complex at a unique vertex of the procapsid conclusively demonstrates the pentameric symmetry of the pRNA and illuminates the relative arrangement of the connector and the pRNA. Additionally, a combination of biochemical and cryo-EM analyses of motor assembly intermediates suggests a sequence of molecular events that constitute the pathway by which the motor assembles on the head, thereby reconciling conflicting data regarding pRNA assembly and stoichiometry. Taken together, these data provide new insight into the assembly, structure, and mechanism of a complex molecular machine.Viruses consist of a protein shell, or capsid, that protects and surrounds their genetic material. Thus, genome encapsidation is a fundamental and essential step in the life cycle of any virus. In dsDNA viruses, powerful molecular motors essentially pump the viral DNA into a preformed protein shell. This article describes how a viral dsDNA packaging motor self-assembles on the viral capsid and provides insight into its mechanism of action.

Dataset Information

Penetration of membrane-containing double-stranded-DNA bacteriophage PM2 into Pseudoalteromonas hosts.

Publications

Penetration of membrane-containing double-stranded-DNA bacteriophage PM2 into Pseudoalteromonas hosts.

Similar Datasets

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