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Viral Ejection Proteins: Mosaically Conserved, Conformational Gymnasts.

Nicholas A Swanson1,2, Chun-Feng D Hou1, Gino Cingolani1

  • 1Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA.

Microorganisms
|March 26, 2022
PubMed
Summary
This summary is machine-generated.

Bacteriophages use internal ejection proteins to deliver DNA into bacteria. Recent cryo-electron microscopy structures reveal how these proteins assemble and change shape during genome delivery.

Keywords:
DNA ejectosomePodoviridaebacteriophage T7cell envelopeejection proteinsgp14gp15gp16internal core proteinsviral genome ejection

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Area of Science:

  • Molecular Biology
  • Virology
  • Structural Biology

Background:

  • Bacterial viruses, or bacteriophages, possess sophisticated mechanisms for injecting their genetic material into host bacteria.
  • Short-tailed phages (Podoviridae) rely on internal virion proteins, also known as ejection or pilot proteins, for genome delivery and infectivity.
  • These ejection proteins are structurally dynamic and difficult to study, making their role in genome ejection less understood than other phage components.

Purpose of the Study:

  • To review the current literature on bacteriophage ejection proteins, focusing on the model phage T7.
  • To elucidate the conformational changes of T7 ejection proteins during the genome ejection process.
  • To predict the conservation and function of these proteins in other Podoviridae phages.

Main Methods:

  • Literature review with a focus on phage T7.
  • Analysis of recent cryo-electron microscopy (cryo-EM) structures of ejection proteins.
  • Comparative analysis to predict protein conservation across Podoviridae.

Main Results:

  • Recent cryo-EM studies have provided insights into the assembly and conformational dynamics of phage ejection proteins.
  • Key structural features of T7 ejection proteins in pre- and post-ejection states have been deciphered.
  • The complex interplay between ejection proteins, portal proteins, and host machinery during genome delivery is highlighted.

Conclusions:

  • Understanding the structure-function relationship of ejection proteins is crucial for deciphering the complex mechanism of phage genome ejection.
  • The conformational flexibility of these proteins is key to their function in navigating the bacterial cell envelope.
  • Further research can elucidate the conservation of these mechanisms across the Podoviridae family.