Plant filamentous viruses from the family Potyviridae belong among the most important plant pathogens. The major component of the virion is the coat protein (CP) which wraps and protects the viral positive-sense single stranded RNA (+ssRNA) viral genome. Together, CP and RNA are organised into a left-handed helical assembly which gives the virus typical rod-like shaped with the length 600-900 nm and the thickness of ~15 nm. Interestingly, CP in the Potyviridae viruses assembles itself into octameric rings which further organize into the long filament (virus like particle, VLP) even without presence of the RNA. Thus, the structure and the mechanism of the filament formation is not only important for understanding the principles of the virus assembly, but it also has the potential for nanobiotechnological applications.

The size and the inherent flexibility of virion has restricted utilisation of standard structural biology techniques in dissecting the structure of the virion. Cryo-electron microscopy has been recently utilized to determine structure of several filamentous viruses. The aim of the diploma thesis will be to describe the molecular mechanisms determining the VLP formation for the case of the plum pox virus (PPV). The student will obtain traning in molecular biology and electron microscopy. She/he will also learn the processing of the cryo-electron microscopy data using single particles analysis approach.

• Frank, Joachim, ed. Electron tomography: three-dimensional imaging with the transmission electron microscope. Springer Science and Business Media, 2013.
• Reimer, Ludwig. Scanning electron microscopy: physics of image formation and microanalysis. Vol. 45. Springer, 2013.