Temperature-dependent nanomechanics and topography of bacteriophage T7.

Abstract

Viruses are nanoscale infectious agents, which may be inactivated by heat treatment. The global molecular mechanisms of virus inactivation and the thermally-induced structural changes in viruses are not fully understood. Here we measured the heat-induced changes in the properties of T7 bacteriophage particles exposed to two-stage (65 degrees C and 80 degrees C) thermal effect, by using AFM-based nanomechanical and topographical measurements. We found that exposure to 65 degrees C led to the release of genomic DNA and to the loss of the capsid tail, hence the T7 particles became destabilized. Further heating to 80 degrees C surprisingly led to an increase in mechanical stability, due likely to partial denaturation of the capsomeric proteins kept within the global capsid arrangement.IMPORTANCE Even though the loss of DNA, caused by heat treatment, destabilizes the T7 phage, its capsid is remarkably able to withstand high temperatures with a more-or-less intact global topographical structure. Thus, partial denaturation within the global structural constraints of the viral capsid may have a stabilizing effect. Understanding the structural design of viruses may help in constructing artificial nanocapsules for the packaging and delivery of materials under harsh environmental conditions.