With Emma Hesketh, and collaborators from the John Innes Centre (Norwich, UK) and the Scripps Research Institute (La Jolla, USA).
Empty virus-like particles (eVLPs) of Cowpea mosaic virus (CPMV) are currently being utilized as reagents in various biomedical and nanotechnology applica- tions. Here, we report the crystal structure of CPMV eVLPs determined using X-ray crystallography at 2.3 A ̊ resolution and compare it with previously re- ported cryo-electron microscopy (cryo-EM) of eVLPs and virion crystal structures. Although the X-ray and cryo-EM structures of eVLPs are mostly similar, there exist significant differences at the C terminus of the small (S) subunit. The intact C terminus of the S sub- unit plays a critical role in enabling the efficient assembly of CPMV virions and eVLPs, but undergoes proteolysis after particle formation. In addition, we report the results of mass spectrometry-based pro- teomics analysis of coat protein subunits from CPMV eVLPs and virions that identify the C termini of S subunits undergo proteolytic cleavages at multi- ple sites instead of a single cleavage site as previ- ously observed.