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- Evilevitch, Alex, et al.
(author)
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Effects of salt concentrations and bending energy on the extent of ejection of phage genomes
- 2008
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In: Biophysical Journal. - : Elsevier BV. - 1542-0086 .- 0006-3495. ; 94:3, s. 1110-1120
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Journal article (peer-reviewed)abstract
- Recent work has shown that pressures inside dsDNA phage capsids can be as high as many tens of atmospheres; it is this pressure that is responsible for initiation of the delivery of phage genomes to host cells. The forces driving ejection of the genome have been shown to decrease monotonically as ejection proceeds, and hence to be strongly dependent on the genome length. Here we investigate the effects of ambient salts on the pressures inside phage-l, for the cases of mono-, di-, and tetravalent cations, and measure how the extent of ejection against a fixed osmotic pressure (mimicking the bacterial cytoplasm) varies with cation concentration. We find, for example, that the ejection fraction is halved in 30 mM Mg21 and is decreased by a factor of 10 upon addition of 1 mM spermine. These effects are calculated from a simple model of genome packaging, using DNA-DNA repulsion energies as determined independently from x-ray diffraction measurements on bulk DNA solutions. By comparing the measured ejection fractions with values implied from the bulk DNA solution data, we predict that the bending energy makes the d- spacings inside the capsid larger than those for bulk DNA at the same osmotic pressure.
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2. |
- French, Roger H., et al.
(author)
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Long range interactions in nanoscale science
- 2010
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In: Reviews of Modern Physics. - 0034-6861. ; 82:2, s. 1887-1944
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Research review (peer-reviewed)abstract
- Our understanding of the “long range” electrodynamic, electrostatic, and polar interactions that dominate the organization of small objects at separations beyond an interatomic bond length is reviewed. From this basic-forces perspective, a large number of systems are described from which one can learn about these organizing forces and how to modulate them. The many practical systems that harness these nanoscale forces are then surveyed. The survey reveals not only the promise of new devices and materials, but also the possibility of designing them more effectively.
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