Alternative mechanism for bacteriophage adsorption to the motile bacterium
            <i>Caulobacter crescentus</i>

Guerrero-Ferreira, Ricardo C.; Viollier, Patrick H.; Ely, Bert; Poindexter, Jeanne S.; Georgieva, Maria; Jensen, Grant J.; Wright, Elizabeth

doi:10.1073/pnas.1012388108

Cited by 116 publications

(148 citation statements)

References 47 publications

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“…Indeed, no retracting pili have been identified in archaea so far, which is also consistent with the apparent lack of genes encoding typical retraction ATPases in the archaeal pilus operons (52,53). A retraction-independent mechanism is utilized by flagellotrophic bacteriophages, which instead harness the energy of flagellar rotation to move along the flagellum toward the cell surface (14,16,17). Notably, the flagella (called archaella in archaea) of Sulfolobus are considerably thicker (ϳ14 nm in diameter [54]) than the LAL14/1 filaments to which SIRV2 binds.…”

Section: Resultsmentioning

confidence: 64%

“…A variety of cell surface structures are known to be targeted by viruses. For example, in the case of bacterial viruses, nearly all components of the cell envelope are known to serve as receptors (7), including lipopolysaccharide (8)(9)(10), pili (11)(12)(13), flagella (14)(15)(16)(17), (lipo-)teichoic acids (18)(19)(20), peptidoglycan (21), or various integral membrane proteins (22)(23)(24). The only archaeal virus for which a potential cellular receptor has been identified is Ch1, infecting the hyperhalophilic host Natrialba magadii (25).…”

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confidence: 99%

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First Insights into the Entry Process of Hyperthermophilic Archaeal Viruses

Quemin

Lucas

Daum

et al. 2013

J Virol

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A decisive step in a virus infection cycle is the recognition of a specific receptor present on the host cell surface, subsequently leading to the delivery of the viral genome into the cell interior. Until now, the early stages of infection have not been thoroughly investigated for any virus infecting hyperthermophilic archaea. Here, we present the first study focusing on the primary interactions between the archaeal rod-shaped virus Sulfolobus islandicus rod-shaped virus 2 (SIRV2) (family Rudiviridae) and its hyperthermoacidophilic host, S. islandicus. We show that SIRV2 adsorption is very rapid, with the majority of virions being irreversibly bound to the host cell within 1 min. We utilized transmission electron microscopy and whole-cell electron cryotomography to demonstrate that SIRV2 virions specifically recognize the tips of pilus-like filaments, which are highly abundant on the host cell surface. Following the initial binding, the viral particles are found attached to the sides of the filaments, suggesting a movement along these appendages toward the cell surface. Finally, we also show that SIRV2 establishes superinfection exclusion, a phenomenon not previously described for archaeal viruses.

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Section: Resultsmentioning

confidence: 64%

mentioning

confidence: 99%

First Insights into the Entry Process of Hyperthermophilic Archaeal Viruses

Quemin

Lucas

Daum

et al. 2013

J Virol

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“…A plausible hypothesis for the function of the Syn5 horn is that it is used by the phage to infect the host. This is the case for the head appendages of the Caulobacter phages Cb13 and CbK (16). Since our data suggest that gp53 (48 kDa) and gp54 (65 kDa) are horn proteins, we tested whether the antibodies used for their identification could reduce or block the infectivity of Syn5.…”

Section: Resultsmentioning

confidence: 99%

“…This is the case for the Caulobacter phages Cb13 and CbK, which have a long head appendage on the vertex opposite the tail and which wrap it tightly around the host flagellum (16). Other phages that use their tails to bind to the host flagella or pili have also been described (18)(19)(20)(21).…”

Section: Discussionmentioning

confidence: 99%

Two Novel Proteins of Cyanophage Syn5 Compose Its Unusual Horn Structure

Raytcheva

Haase-Pettingell

Piret

et al. 2014

J Virol

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The marine cyanophage Syn5 can be propagated to a high titer in the laboratory on marine photosynthetic Synechococcus sp. strain WH8109. The purified particles carry a novel slender horn structure projecting from the vertex opposite the tail vertex. The genome of Syn5 includes a number of genes coding for novel proteins. Using immune-electron microscopy with gold-labeled antibodies, we show that two of these novel proteins, products of genes 53 and 54, are part of the horn structure. A third novel protein, the product of gene 58, is assembled onto the icosahedral capsid lattice. Characterization of radioactively labeled precursor procapsids by sucrose gradient centrifugation shows that there appear to be three classes of particles-procapsids, scaffold-deficient procapsids, and expanded capsids. These lack fully assembled horn appendages. The horn presumably assembles onto the virion just before or after DNA packaging. Antibodies raised to the recombinant novel Syn5 proteins did not interfere with phage infectivity, suggesting that the functions of these proteins are not directly involved in phage attachment or infection of the host WH8109. The horn structure may represent some adaption to the marine environment, whose function will require additional investigation.

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“…Caulobacter crescentus is a Gram-negative, oligotrophic bacterium that expresses polar type IVb pili in the swarmer stage of its dimorphic life cycle [2]. These pili are known to be involved in surface attachment at the swarmer to sessile transition [3] and are additionally utilized by the prolate siphophage ϕCbK in the initial stages of infection by attaching to the pilus portals [4]. Although there is no known homologue to the type IVa retraction ATPase in the C. crescentus genome, it has been hypothesized that pilus retraction aids in both of these functions [2,5].…”

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confidence: 99%

Analysis of Phage-Pilus Interactions in Caulobacter crescentus

et al. 2016

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Many bacterial species express external filamentous structures known as pili that are essential to numerous biological processes . Because of their roles in motility, biofilm formation, and surface colonizaion, pili often serve as important virulence factors for pathogenic bacteria [1]. Caulobacter crescentus is a Gram-negative, oligotrophic bacterium that expresses polar type IVb pili in the swarmer stage of its dimorphic life cycle [2]. These pili are known to be involved in surface attachment at the swarmer to sessile transition [3] and are additionally utilized by the prolate siphophage ϕCbK in the initial stages of infection by attaching to the pilus portals [4]. Although there is no known homologue to the type IVa retraction ATPase in the C. crescentus genome, it has been hypothesized that pilus retraction aids in both of these functions [2,5]. We investigated the role of pilus retraction in ϕCbK attachment using bacteriophage adsorption assays, cryo-correlative light and electron microscopy (cryo-CLEM), and cryo-electron microscopy and tomography (cryo-EM and cryo-ET).Bacteriophage adsorption assays were carried out after the addition of carbonyl cyanide mchlorophenylhydrazone (CCCP), a proton-ionophore that dissipates the proton motive force (PMF). Our results indicate that ϕCbK adsorption is severely compromised at CCCP concentrations above 5 µM, implying that ϕCbK adsorption is dependent upon the PMF, which has been shown to be involved in type IVa pilus retraction [6]. We then utilized cryo-CLEM and cryo-ET to further characterize the interactions between pili and ϕCbK. C. crescentus NA1000 spmX::spmX-mCherry cells were infected with GFP-ϕCbK in which GFP is fused with the major capsid protein, then applied to copper 200 mesh grids with R 2/1 Quantifoil carbon supports and plunge frozen in liquid ethane. Grids were imaged using a Leica EM Cryo CLEM system and a JEOL JEM-2200FS 200 kV TEM equipped with an incolumn Omega energy filter and Direct Electron DE-20 camera. Tilt series were acquired at 2° increments with a range of -62° to +62° using SerialEM [7] and tomographic reconstructions were generated with IMOD [8].Cryo-CLEM experiments allow us to identify events in which mCherry-labeled cells are being infected with GFP-labeled ϕCbK by cryo-fluorescence microscopy ( Fig. 1A and 1B), then correlate and locate these events for cryo-EM data collection (Fig. 1C). Using cryo-ET, we found that phage tail fibers interact with extended pilus filaments at early timepoints of infection (Fig. 2). Combined with adsorption assays, these results suggest that the ϕCbK tail fiber adsorbs to the pilus filament of the host cell and pilus retraction brings the phage to the site of irreversible attachment at the pilus portal. We therefore hypothesize that the type IVb pili of C. crescentus are capable of retraction. Future research will investigate the possible mechanisms that control pilus retraction and determine the structure of the machinery associated with pilus secretion and retraction.

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Alternative mechanism for bacteriophage adsorption to the motile bacterium Caulobacter crescentus

Cited by 116 publications

References 47 publications

First Insights into the Entry Process of Hyperthermophilic Archaeal Viruses

First Insights into the Entry Process of Hyperthermophilic Archaeal Viruses

Two Novel Proteins of Cyanophage Syn5 Compose Its Unusual Horn Structure

Analysis of Phage-Pilus Interactions in Caulobacter crescentus

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