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Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins
09:40

Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins

Published on: June 11, 2015

Multifunctional roles of a bacteriophage phi 29 morphogenetic factor in assembly and infection

Daniel N Cohen1, Stephen E Erickson, Ye Xiang

  • 1Department of Microbiology, University of Minnesota Medical School, University of Minnesota, Minneapolis, MN 55455, USA.

Journal of Molecular Biology
|April 9, 2008
PubMed

Insights

The Bacillus subtilis bacteriophage phi 29 gene 13 product (gp13), a low copy number protein, was identified in the virion. This protein is crucial for phi 29 infectivity, likely acting as a pilot protein during cell wall penetration.

Area of Science:

  • Virology
  • Structural Biology
  • Bacteriophage Research

Background:

  • Low copy number proteins are vital for macromolecular complex function, despite their small mass fraction.
  • The Bacillus subtilis bacteriophage phi 29 gene 13 product (gp13) was previously undetected in the virion.

Purpose of the Study:

  • To identify and localize the previously undetected gp13 within the phi 29 virion.
  • To investigate the role of gp13 in phi 29 particle assembly and infectivity.

Main Methods:

  • Western blots and immuno-electron microscopy were used to detect and localize gp13.
  • Analysis of phi 29 particles, DNA-free particles, purified tails, and defective particles from suppressor-sensitive mutants.

Main Results:

  • gp13 was identified and localized to the distal tip of the phi 29 tail knob.
  • Few copies of gp13 were detected in various phi 29 particle preparations.
  • Particles lacking intact gp13 (sus13(342) and sus13(330)) were morphologically similar to wild-type phi 29 but non-infectious.

Conclusions:

  • gp13 is essential for phi 29 infectivity and is located at a strategic position on the tail knob.
  • gp13's predicted homology to metalloproteases suggests a role in cell wall depolymerization as a pilot protein.
  • gp13 may function as a genome restraint plug and facilitate host cell membrane interaction for genome injection.

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