DNA Heats Up: Energetics of Genome Ejection from Phage Revealed by Isothermal Titration Calorimetry

Meerim Jeembaeva, Bengt Jönsson, Martin Castelnovo, Alex Evilevitch

Research output: Contribution to journalArticlepeer-review

Abstract

Most bacteriophages are known to inject their double-stranded DNA into bacteria upon receptor binding in an essentially spontaneous way. This downhill thermodynamic process from the intact virion to the empty viral capsid plus released DNA is made possible by the energy stored during active packaging of the genome into the capsid. Only indirect measurements of this energy have been available until now, using either single-molecule or osmotic suppression techniques. In this work, we describe for the first time the use of isothermal titration calorimetry to directly measure the heat released (or, equivalently, the enthalpy) during DNA ejection from phage λ, triggered in solution by a solubilized receptor. Quantitative analyses of the results lead to the identification of thermodynamic determinants associated with DNA ejection. The values obtained were found to be consistent with those previously predicted by analytical models and numerical simulations. Moreover, the results confirm the role of DNA hydration in the energetics of genome confinement in viral capsids.

Original languageEnglish (US)
Pages (from-to)1079-1087
Number of pages9
JournalJournal of Molecular Biology
Volume395
Issue number5
DOIs
StatePublished - Feb 5 2010

Keywords

  • bacteriophage
  • capsid
  • enthalpy
  • genome ejection
  • isothermal titration calorimetry

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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