Molecular architecture and life cycle of filamentous viruses

Polak Martin¹, Novacek Jiri¹, Plchova Helena², Novakova Slavomira³, Podobnik Marjetka⁴, Sink Andreja⁴

1Core Facility Cryo-electron Microscopy and Tomography CEITEC, Masaryk University, ČR

²Institute of Experimental Botany, AS ČR

³Department of Plant Virology, AS SR

4Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Slovenia

Potato virus X (PVX) is a member of the family Alphaflexiviridae in the genus Potexvirus. It infects several solanaceous crops including potato (it can cause yield losses of up to 15% in some varieties), tomato and tobacco. Symptoms produced by PVX are

Institute of Experimental Botany AS CRvariable, depending on the strain and host plant. In general, plants often do not exhibit symptoms, but the virus can cause symptoms of mild mottling, chlorosis, mosaic or decreased leaf size. It can be mechanically transmitted.

PVX has a monopartite plus-sense single stranded RNA ((+)ssRNA) of approximately 6.4 kb (Skryabin et al., 1988). PVX virions are flexible rods 515 nm long and 13.5 nm in diameter, consisting of approximately 1350 helically folded identical coat protein (CP) subunits and viral RNA packed between its turns (Tollin and Wilson, 1988).

So far, only low-resolution structure of PVX virion has been determine providing limited information about CP-CP and CP-RNA interactions. The aim of this project is (1) to determine the near-atomic structure of Potato virus X and CP-CP and CP-RNA interacting amino acids and (2) to define the surface exposed regions/loops and test them for possible tolerance of inserted peptides. PVX structure and interacting amino acids was analyzed using cryo-electron microscopy.