The nucleocapsid of bacteriophage phi 6 penetrates the host cytoplasmic membrane.

Romantschuk, Martin; Olkkonen, Vesa M.; Bamford, Dennis H.

doi:10.1002/j.1460-2075.1988.tb03014.x

Cited by 52 publications

(51 citation statements)

References 53 publications

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“…Thus, wild-type P. syringue pv. phaseolicdu cells do not adsorb phage in the presence of sodium azide and other uncoupling agents suggesting that the pilus is retracted in the absence of a membrane potential (Romantschuk & Barnford, 1985;Romantschuk et al, 1988). This effect was not observed in phage-resistant super-piliated strains used (M. Romantschuk, unpublished).…”

Section: Discussionmentioning

confidence: 99%

Pilus-mediated adsorption of Pseudomonas syringae to the surface of host and non-host plant leaves

Romantschuk

Nurmiaho‐Lassila

Roine

et al. 1993

Journal of General Microbiology

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~ ~~Adsorption of cells of a variety of Pseudomonas syvingae pathovars to the leaf surface of host and non-host plants was measured. The strains used were sensitive to the pilus-specific bacteriophage #ti. Phage-resistant non-piliated mutants were isolated and found to have reduced ability to adsorb to plant surfaces. The pilus-mediated adsorption was not host-specific. Piliated strains adsorbed well to both host and non-host plants. Scanning electron microscopy of the P, syringae pathovar syringae strain R32 and the pathovar phaseolicola strain HBlOY revealed a difference between these strains in the distribution of the bacterial cells over the lower bean leaf surface. P. syvingae pv. syvingae spread evenly over the leaf surface whereas P. syringae pv. phaseolicolu adsorbed preferentially to the stomata. No such localization was observed on chloroform-treated leaves, where the cells of both pathovars were evenly distributed. Adsorption of bacteria to leaf disks was independent of divalent cations, and no specific ionic conditions were required.

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Section: Discussionmentioning

confidence: 99%

Pilus-mediated adsorption of Pseudomonas syringae to the surface of host and non-host plant leaves

Romantschuk

Nurmiaho‐Lassila

Roine

et al. 1993

Journal of General Microbiology

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“…6). The fluorescent spots appear slowly and increase with time, but there are rarely more than two spots per cell, which is the same number of virus particles that enter piliated cells (4). The spots do not move much and persist to the end of the infection cycle.…”

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Role of host protein glutaredoxin 3 in the control of transcription during bacteriophage Φ2954 infection

Qiao¹,

Qiao²,

Sun³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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Bacteriophage Φ2954 contains three dsRNA genomic segments, designated L, M, and S. The RNA is located inside a core particle composed of multiple copies of a major structural protein, an RNA-dependent RNA polymerase, a hexameric NTPase, and an auxiliary protein. The core particle is covered by a shell of protein P8, and this structure is enclosed within a lipid-containing membrane. We have found that normal infection of the host Pseudomonas syringae is dependent on the action of a host protein, glutaredoxin 3 (GrxC). GrxC removes the P8 shell from the infecting particle and binds to the inner core. Removal of P8 activates the transcription of segments S and M, whereas binding of GrxC to the core particle activates the transcription of segment L. The differences in transcription behavior are due to the preference of the polymerase for G as the first base of the transcript. Transcripts of segments S and M begin with GCAA, whereas those of segment L begin with ACAA. The binding of GrxC to the particle results in changes in polymerase activity. Mutations resulting in independence of GrxC are found in the gene for protein P1, the major structural protein of the inner core particle.B acteriophage Φ2954 is a member of the Cystoviridae, a family of bacteriophages that have genomes of three double-stranded RNA molecules, L, M, and S, packaged inside a polyhedral capsid structure covered by a lipid-containing membrane (1). Φ6 was the first member of this family to be discovered (2). A number of relatives of Φ6 were isolated in 1999 (3). Some of these relatives were closely related to Φ6, whereas others were more distantly related and attached to host cells through rough LPS rather than the type IV pili used by Φ6. Φ2954 is rather similar to Φ12, a member of the latter group, but it attaches to host cells by means of the type IV pilus. Cystoviridae infect Gram-negative bacteria, primarily Pseudomonas syringae and its relatives. Φ6 has been the primary subject of studies of the Cystoviridae.Φ6 infects by fusing its membranes with the outer membrane of the host cells, breaching the cell wall through the action of muramidases, and finally having the nucleocapsid of the virion enter the host cell (4). The nucleocapsid loses its outer shell of protein P8 to expose the viral core. The core contains an RNA-dependent RNA polymerase that synthesizes transcripts that are released from the core to program the synthesis of phage proteins (5). How the P8 shell of Φ6 is removed in vivo is unclear; however, P8 can be removed in vitro by incubation with calcium-chelating agents, such as EGTA. In that case, transcription of segments S and M is activated. Transcription of segment L does not occur, because the phage polymerase prefers G as the second nucleotide in the transcript, and segment L begins with GUAA, whereas segments S and M begin with GGAA. A host protein, YajQ, is required for the activation of segment L transcription of Φ6 (6). The binding of YajQ to protein P1 of the core capsid apparently activates the polymerase P2 located i...

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“…The virion muramidase P5 digests a pathway in the cell wall so as to allow the entry of the nucleocapsid into the cell. Protein P8 is removed from the particle by an unknown mechanism and is eventually digested (16). The core particle is capable of transcribing genomic segments S and M, but it is covered by YajQ, which activates the transcription of genomic segment L. The amount of YajQ in the cell is limited, and as new particles are formed and filled, a few are covered by YajQ, but most of the new core particles are covered by protein P8 after minus-strand synthesis on the templates of packaged transcripts.…”

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Interaction of a Host Protein with Core Complexes of Bacteriophage Φ6 To Control Transcription

Qiao¹,

Sun²,

Qiao³

et al. 2010

J Virol

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Bacteriophages of the familyBacteriophage ⌽6 is a member of the family Cystoviridae. The virion contains a genome of three segments (S, M, and L) of double-stranded RNA (dsRNA), which are enclosed in a polyhedral core along with polymerase molecules (20). The core is covered by a shell of a single protein species, P8, and this assemblage is enclosed in a lipid-containing membrane (5, 21). The virus propagates in plant pathogen Pseudomonas syringae. Genomic segment L codes for proteins P1, P2, P4, and P7, which are expressed early in infection and assemble to form the core particles (9). Transcripts of segment L along with those of segments S and M are observed early in infection. At later times, the amount of L transcript increases somewhat, while the amounts of S and M increase greatly. Most of the late-period L transcripts are found in packaged RNA, while the S and M transcripts are primarily found as free plus strands. The S and M segments code for proteins that are expressed later in infection (8). Core particles of the virus have in vitro transcriptase activity for genomic segments S and M (12, 13). The polymerase of ⌽6 shows a preference for G as opposed to U for the second nucleotide in its transcripts (1,19). Segments S and M begin with GG, while segment L begins with GU. Incubation with host protein YajQ results in the transcription of segment L (15). Previous work has shown that productive infection is dependent upon the presence of YajQ in the host cells and that the protein binds to P1, which is the major structural protein of the virus core particle (15). Mutants of ⌽6 that are not dependent on YajQ were isolated and were shown to have changes in P1 and in P2, the virion polymerase. Our working model for the activity of YajQ is as follows. The virus attaches to the host type IV pilus, which retracts so as to bring the virion to the surface of the outer membrane, where the viral membrane fuses so as to allow the nucleocapsids to enter the periplasmic space. The virion muramidase P5 digests a pathway in the cell wall so as to allow the entry of the nucleocapsid into the cell. Protein P8 is removed from the particle by an unknown mechanism and is eventually digested (16). The core particle is capable of transcribing genomic segments S and M, but it is covered by YajQ, which activates the transcription of genomic segment L. The amount of YajQ in the cell is limited, and as new particles are formed and filled, a few are covered by YajQ, but most of the new core particles are covered by protein P8 after minus-strand synthesis on the templates of packaged transcripts. Transcription of L continues during the late period of infection, but most of the L transcript is found in packaged particles and little L transcript is seen as single-stranded RNA (15).In this study, we attempted to visualize the in vivo interaction of YajQ with virus particles to facilitate an understanding of the amount and the extent of binding, the timing, and the specificity of the interaction. The interaction of YajQ with core particl...

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The nucleocapsid of bacteriophage phi 6 penetrates the host cytoplasmic membrane.

Cited by 52 publications

References 53 publications

Pilus-mediated adsorption of Pseudomonas syringae to the surface of host and non-host plant leaves

Pilus-mediated adsorption of Pseudomonas syringae to the surface of host and non-host plant leaves

Role of host protein glutaredoxin 3 in the control of transcription during bacteriophage Φ2954 infection

Interaction of a Host Protein with Core Complexes of Bacteriophage Φ6 To Control Transcription

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