Elsevier, Journal of Molecular Biology, 1(405), p. 18-23
DOI: 10.1016/j.jmb.2010.10.039
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Based on atomic force microscopy nanoindentation measurements of phage λ, we previously proposed a minimal model describing the effect of water hydrating DNA that strengthens viral capsids against external deformation at wild-type DNA packing density. Here, we report proof of this model by testing the prediction that DNA hydration forces can be dramatically decreased by addition of multivalent ions (Mg(2+) and Sp(4+)). These results are explained using a DNA hydration model without adjustable parameters. The model also predicts the stiffness of other DNA-filled capsids, which we confirm using bacteriophage ϕ29 and herpes simplex virus type 1 particles.