A Cut above the Rest: Characterization of the Assembly of a Large Viral Icosahedral Capsid

Reilly, Erin R; Abajorga, Milky K; Kiser, Cory; Redzuan, Nurul Humaira Mohd; Haidar, Zein; Adams, Lily E.; Diaz, Randy; Pinzon, Juliana A; Hudson, André O.; Black, Lindsay W.; Hsia, Ru-ching; Weintraub, Susan T.; Thomas, Julie A.

doi:10.3390/v12070725

Cited by 12 publications

(8 citation statements)

References 47 publications

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“…Since the phiKZ cell infection is resistant to bacterial defense systems on each stage [ 15 ], and the pseudo-nucleus did not form immediately, it can be hypothesized that the protection of the phage DNA at the beginning of the infection is carried out by the RC shell. Somewhat similar structures were observed in cells infected by the giant phage SPN3US from the 5th min of infection [ 34 ], which were suggested to be phage proheads maturing within the course of infection. However, the transcription profile for the phiKZ phage was determined earlier [ 3 ], and no virion protein genes transcribed at the 5th min of the phiKZ infection were found, so we think that the RCs that were observed here mark the phage’s entrance.…”

Section: Discussionmentioning

confidence: 56%

Maturation of Pseudo-Nucleus Compartment in P. aeruginosa, Infected with Giant phiKZ Phage

Danilova

Belousova

Moiseenko

et al. 2020

Viruses

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The giant phiKZ phage infection induces the appearance of a pseudo-nucleus inside the bacterial cytoplasm. Here, we used RT-PCR, fluorescent in situ hybridization (FISH), electron tomography, and analytical electron microscopy to study the morphology of this unique nucleus-like shell and to demonstrate the distribution of phiKZ and bacterial DNA in infected Pseudomonas aeruginosa cells. The maturation of the pseudo-nucleus was traced in short intervals for 40 min after infection and revealed the continuous spatial separation of the phage and host DNA. Immediately after ejection, phage DNA was located inside the newly-identified round compartments; at a later infection stage, it was replicated inside the pseudo-nucleus; in the mature pseudo-nucleus, a saturated internal network of filaments was observed. This network consisted of DNA bundles in complex with DNA-binding proteins. On the other hand, the bacterial nucleoid underwent significant rearrangements during phage infection, yet the host DNA did not completely degrade until at least 40 min after phage application. Energy dispersive x-ray spectroscopy (EDX) analysis revealed that, during the infection, the sulfur content in the bacterial cytoplasm increased, which suggests an increase of methionine-rich DNA-binding protein synthesis, whose role is to protect the bacterial DNA from stress caused by infection.

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Section: Discussionmentioning

confidence: 56%

Maturation of Pseudo-Nucleus Compartment in P. aeruginosa, Infected with Giant phiKZ Phage

Danilova

Belousova

Moiseenko

et al. 2020

Viruses

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show abstract

“…12f-l). Notably, similarly sized compartments have been observed by thin-section transmission electron microscopy of jumbo phage PhiKZ and SPN3US infecting Pseudomonas aeruginosa and Salmonella, respectively 18,19 . Further work will be required to determine whether USBs represent unproductive infections that failed to pierce the inner membrane of the host, or instead represent a mechanism to protect the phage genome early in infection, before chimallin production and nuclear shell assembly.…”

Section: Discussionmentioning

confidence: 89%

Architecture and self-assembly of the jumbo bacteriophage nuclear shell

Laughlin

Deep

Prichard

et al. 2022

Nature

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Bacteria encode myriad defences that target the genomes of infecting bacteriophage, including restriction–modification and CRISPR–Cas systems1. In response, one family of large bacteriophages uses a nucleus-like compartment to protect its replicating genomes by excluding host defence factors2–4. However, the principal composition and structure of this compartment remain unknown. Here we find that the bacteriophage nuclear shell assembles primarily from one protein, which we name chimallin (ChmA). Combining cryo-electron tomography of nuclear shells in bacteriophage-infected cells and cryo-electron microscopy of a minimal chimallin compartment in vitro, we show that chimallin self-assembles as a flexible sheet into closed micrometre-scale compartments. The architecture and assembly dynamics of the chimallin shell suggest mechanisms for its nucleation and growth, and its role as a scaffold for phage-encoded factors mediating macromolecular transport, cytoskeletal interactions, and viral maturation.

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“…16e-k). Notably, similarly sized compartments have been observed by thin-section TEM of jumbo phage ΦKZ and SPN3US infecting P. aeruginosa and Salmonella, respectively (18,19). Further work will be required to determine whether USBs represent unproductive infections that failed to pierce the inner membrane of the host, or instead represent a mechanism to protect a phage's genome early in infection, prior to chimallin production and nuclear shell assembly.…”

Section: Biogenesis Of the Phage Nucleus And Putative Pre-nuclearmentioning

confidence: 98%

Architecture and self-assembly of the jumbo bacteriophage nuclear shell

Laughlin¹,

Deep

Prichard³

et al. 2022

Preprint

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Bacteria encode myriad defenses that target the genomes of infecting bacteriophage, including restriction-modification and CRISPR/Cas systems. In response, one family of large bacteriophage employs a nucleus-like compartment to protect their replicating genomes by excluding host defense factors. However, the principle composition and structure of this compartment remain unknown. Here, we find that the bacteriophage nuclear shell assembles primarily from one protein, termed chimallin. Combining cryo-electron tomography of nuclear shells in bacteriophage-infected cells and cryo-electron microscopy of a minimal chimallin compartment in vitro, we show that chimallin cooperatively self-assembles as a flexible sheet into closed micron-scale compartments. The architecture and assembly dynamics of the chimallin shell suggest mechanisms for its nucleation and growth, and its role as a scaffold for phage-encoded factors mediating macromolecular transport, cytoskeletal interactions, and viral maturation.

show abstract

A Cut above the Rest: Characterization of the Assembly of a Large Viral Icosahedral Capsid

Cited by 12 publications

References 47 publications

Maturation of Pseudo-Nucleus Compartment in P. aeruginosa, Infected with Giant phiKZ Phage

Maturation of Pseudo-Nucleus Compartment in P. aeruginosa, Infected with Giant phiKZ Phage

Architecture and self-assembly of the jumbo bacteriophage nuclear shell

Architecture and self-assembly of the jumbo bacteriophage nuclear shell

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