Low-Temperature Adaptation Targets Genome Packing Reactions in an Icosahedral Single-Stranded DNA Virus

Elizabeth T. Ogunbunmi, Samuel D. Love, Katherine A. Rhodes, Adriana Morales, Margaret H. Wilch, Jeremy Jonas, Bentley A. Fane

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


øX174, G4, and α3 represent the three sister genera of a Microviridae subfamily. α3-like genomes are considerably larger than their sister genera genomes, yet they are packaged into capsids of similar internal volumes. They also contain multiple A*genes, which are nested within the larger A gene reading frame. Although unessential under most conditions, A*proteins mediate the fidelity of packaging reactions. Larger genomes and multiple A*genes may indicate that genome packaging is more problematic for α3-like viruses, especially at lower temperatures, where DNA persistence lengths would be longer. Unlike members of the other genera, which reliably form plaques at 20°C, α3-like phages are naturally cold sensitive below 28°C. To determine whether there was a connection between the uniquely α3-like genome characteristics and the cold-sensitive phenotype, the α3 assembly pathway was characterized at low temperature. Although virions were not detected, particles consistent with off-pathway packaging complexes were observed. In a complementary evolutionary approach, α3 was experimentally evolved to grow at progressively lower temperatures. The two major responses to cold adaptation were genome reduction and elevated A*gene expression.

Original languageEnglish (US)
Article numbere01970-21
JournalJournal of virology
Issue number7
StatePublished - Apr 2022


  • DNA packaging
  • Microviridae
  • bacteriophage evolution
  • experimental evolution
  • single-stranded DNA

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Insect Science
  • Virology


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