The effect of genome length on ejection forces in bacteriophage lambda

Virology. 2006 May 10;348(2):430-6. doi: 10.1016/j.virol.2006.01.003. Epub 2006 Feb 15.

Abstract

A variety of viruses tightly pack their genetic material into protein capsids that are barely large enough to enclose the genome. In particular, in bacteriophages, forces as high as 60 pN are encountered during packaging and ejection, produced by DNA bending elasticity and self-interactions. The high forces are believed to be important for the ejection process, though the extent of their involvement is not yet clear. As a result, there is a need for quantitative models and experiments that reveal the nature of the forces relevant to DNA ejection. Here, we report measurements of the ejection forces for two different mutants of bacteriophage lambda, lambdab221cI26 and lambdacI60, which differ in genome length by approximately 30%. As expected for a force-driven ejection mechanism, the osmotic pressure at which DNA release is completely inhibited varies with the genome length: we find inhibition pressures of 15 atm and 25 atm, for the short and long genomes, respectively, values that are in agreement with our theoretical calculations.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bacteriophage lambda / genetics*
  • Bacteriophage lambda / physiology*
  • Biophysical Phenomena
  • Biophysics
  • DNA, Viral / chemistry
  • DNA, Viral / physiology
  • Genome, Viral*
  • Models, Biological
  • Mutation
  • Nucleic Acid Conformation
  • Osmotic Pressure
  • Pressure
  • Virus Assembly / physiology

Substances

  • DNA, Viral