Mutagenic analysis of a DNA translocating tube's interior surface

Aaron P. Roznowski, Julia M. Fisher, Bentley A. Fane

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Bacteriophage-φX174 uses a decamer of DNA piloting proteins to penetrate its host. These proteins oligomerize into a cell wall-spanning tube, wide enough for genome passage. While the inner surface of the tube is primarily lined with inward-facing amino acid side chains containing amide and guanidinium groups, there is a 28 Å-long section near the tube's C-terminus that does not exhibit this motif. The majority of the inward-facing residues in this region are conserved across the three φ-X174-like clades, suggesting that they play an important role during genome delivery. To test this hypothesis, and explore the general function of the tube's inner surface, non-glutamine residues within this region were mutated to glutamine, while existing glutamine residues were changed to serine. Four of the resulting mutants had temperature-dependent phenotypes. Virion assembly, host attachment, and virion eclipse, defined as the cell's ability to inactivate the virus, were not aected. Genome delivery, however, was inhibited. The results support a model in which a balance of forces governs genome delivery: potential energy provided by the densely packaged viral genome and/or an osmotic gradient move the genome into the cell, while the tube's inward facing glutamine residues exert a frictional force, or drag, that controls genome release.

Original languageEnglish (US)
Article number670
Issue number6
StatePublished - Jun 2020


  • DNA pilot protein
  • Microviridae
  • Penetration
  • φ-X174

ASJC Scopus subject areas

  • Infectious Diseases
  • Virology


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