Mutagenic Analysis of a DNA Translocating Tube's Interior Surface

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

Research output: Contribution to journalArticle

Abstract

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 ϕX174-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 affected. 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)
JournalViruses
Volume12
Issue number6
DOIs
StatePublished - Jun 22 2020

Keywords

  • DNA pilot protein
  • microviridae
  • penetration
  • ϕX174

ASJC Scopus subject areas

  • Infectious Diseases
  • Virology

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