T7-like Viral Infection of Cyanobacteria Visualized by Electron Cryo-tomography Single Particle Analysis

Abstract

Electron cryo-tomography single particle analysis is a method to distinguish heterogeneous bio-macromolecules and analyze them, which take various conformational changes in the sample solution. We apply this method for studying the structural changes of the T7-like virus, P-SSP7 during the infection of marine cyanobacteria, Prochrolococcus MED4. We found that there are three states in the viral adsorption to the cell surface. The virus changes the conformation of the spike fibers with these steps and finally injects the viral DNA into the host cell through the tail vertically connected to the cell surface. In addition, a comparison with the high-resolution structures from the conventional single particle analysis showed a relationship between the conformational changes of the spike fibers and the DNA gating in the tail. Here, we describe the methods of image processing and present the biological results.