Matrix proteins play a central role in the assembly of enveloped pleomorphic viruses. In order to study matrix protein function during assembly, cryo-electron microscopy and tomography studies were carried out on two virus families. Studies of coronavirus virus-like particles and virions revealed that the matrix protein M forms a two-dimensional network of endodornain-Iinked homodimers at the membrane. Structural differences were detected between M on membranes with rigid positive curvature and M on flaccid membranes with variable curvature. Studies of filamentous and round influenza A virus revealed structural and functional differences in the homodimeric matrix protein Ml that were associated with differences in local membrane curvature. The conformational change happened more commonly on filamentous particles than on spherical. In both virus families matrix proteins were found to control membrane bending and rigidity through a process that appears to involve ribonucleoprotein-dependent conformational changes. Both influenza Ml and coronavirus M lost rigid membrane bending activity upon exposure to pH 5.0, demonstrating that the interactions that are proposed to lead to budding can be reversed under conditions that simulate the endosomal environment. Together, these observations help to explain how matrix proteins are able to produce sufficient force to drive the budding process through homotypic and heterotypic intramolecular interactions, and how the structural changes that drive egress can be reversed to facilitate entry.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:559252 |
| Date | January 2011 |
| Creators | Kiss, Gabriella |
| Publisher | University of Reading |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0023 seconds