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Cryo-electron microscopy structure of the filamentous bacteriophage IKe

Jingwei Xu1,2,3,4, Nir Dayan5, Amir Goldbourt6

  • 1Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing 100084, China.

Proceedings of the National Academy of Sciences of the United States of America
|March 2, 2019
PubMed

Insights

The cryo-electron microscopy structure of the filamentous bacteriophage IKe reveals its micrometer-long viral particle. This study details the atomic model of its major coat protein and capsid structure, offering insights into viral assembly and genome packaging.

Area of Science:

  • Structural Biology
  • Virology
  • Microbiology

Background:

  • The filamentous bacteriophage IKe infects *Escherichia coli* via IncN pili.
  • Understanding viral structure is crucial for comprehending infection mechanisms.

Purpose of the Study:

  • To determine the high-resolution cryo-electron microscopy structure of the IKe bacteriophage.
  • To build an atomic model of the major coat protein (p8) and analyze capsid assembly.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) was used to image the IKe viral particle.
  • High-resolution (3.4 Å) structural data enabled atomic model building of the major coat protein (p8).

Main Results:

  • The IKe viral particle is micrometer-long, with a right-handed helical capsid cylinder formed by p8 proteins.
  • The capsid's inner surface is positively charged, interacting with the single-stranded DNA genome, which adopts an unusual left-handed helical structure.
  • Hydrophobic residues and π-π interactions between specific amino acids maintain capsid integrity, similar to other filamentous phages.

Conclusions:

  • The study provides a detailed atomic model of the IKe bacteriophage structure.
  • Structural similarities, like π-π interactions, suggest conserved assembly mechanisms among filamentous phages despite sequence divergence.
Keywords:
cryo-EM structurefilamentous virushelical reconstructionsingle-stranded circular DNAsymmetry mismatch

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