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Bacteriophages, or phages, are viruses that specifically infect bacteria, utilizing their genetic material to hijack host cellular machinery for replication. DNA bacteriophages employ single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA) genomes. These phages exhibit diverse replication strategies and host interactions, influencing their ecological roles and applications in biotechnology and medicine.ssDNA BacteriophagesssDNA phages, with their small genomes, utilize unique strategies to...
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Bacteriophages, or phages, are viruses that specifically infect bacteria. Among them, T-even bacteriophages, such as T4, exhibit a well-characterized lytic replication cycle in Escherichia coli (E. coli). This process ensures the rapid proliferation of the virus while ultimately leading to the destruction of the bacterial host.Attachment and DNA InjectionThe infection process begins with the recognition and binding of the T4 phage to the E. coli cell surface. Tail fibers of the phage...
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Among the three main modes of HGT—transformation, conjugation, and transduction—transduction is unique in that it is mediated by bacteriophages, or bacterial viruses.Transduction occurs in two ways. Generalized transduction occurs during the lytic cycle of a bacteriophage infection. In this process, bacteriophages infect bacterial cells, replicate within them, and ultimately cause cell lysis, releasing newly assembled virions. Occasionally, random fragments of the bacterial genome...
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Structural changes in bacteriophage T7 upon receptor-induced genome ejection.

Wenyuan Chen1,2, Hao Xiao1,3, Li Wang4

  • 1Key Laboratory for Matter Microstructure and Function of Hunan Province, Key Laboratory of Low-dimensional Quantum Structures and Quantum Control, School of Physics and Electronics, Hunan Normal University, Changsha 410082, China.

Proceedings of the National Academy of Sciences of the United States of America
|September 10, 2021
PubMed
Summary
This summary is machine-generated.

This study reveals the near-atomic structure of bacteriophage T7, detailing its DNA ejection machinery. The findings elucidate how bacteriophage T7 proteins form a channel to deliver genomic DNA into host cells.

Keywords:
bacteriophagesejection proteinsgenome deliverylipopolysaccharide

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Area of Science:

  • Structural Biology
  • Microbiology
  • Virology

Background:

  • Bacteriophages, viruses that infect bacteria, utilize complex protein machinery for DNA delivery.
  • The bacteriophage T7 ejection apparatus, comprising portal-tail complex and ejection proteins, is crucial for initiating infection by forming a transenvelope channel.

Purpose of the Study:

  • To determine the near-atomic structure of the mature bacteriophage T7, including its ejection proteins.
  • To elucidate the structural basis of DNA delivery mechanism through the bacteriophage T7 portal-tail complex and ejection proteins.
  • To investigate the interaction between bacteriophage T7 and its host cell receptor, lipopolysaccharide.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) for near-atomic resolution reconstruction of bacteriophage T7.
  • Structural analysis of full and empty T7 particles in complex with lipopolysaccharide.
  • Detailed examination of the protein components involved in DNA ejection.

Main Results:

  • The bacteriophage T7 ejection proteins assemble into a core structure consisting of gp16, gp15, and gp14 rings.
  • The tail nozzle of bacteriophage T7 opens upon interaction with lipopolysaccharide, with gp14 anchoring and extending the nozzle.
  • gp16 possesses a lytic transglycosylase domain, and distinct hydrophobic/hydrophilic channel components (gp16/gp15) suggest specialized roles in traversing bacterial envelopes.

Conclusions:

  • The study provides unprecedented structural insights into the bacteriophage T7 DNA ejection mechanism.
  • The findings highlight the conformational adaptability of gp15 and gp16 in forming the transenvelope channel.
  • The research elucidates the role of specific bacteriophage T7 proteins in breaching the bacterial cell envelope during infection.