Thermal remodelling of Alternanthera mosaic virus virions and virus-like particles into protein spherical particles

The present work addresses the thermal remodelling of flexible plant viruses with a helical structure and virus-like particles (VLPs). Here, for the first time, the possibility of filamentous Alternanthera mosaic virus (AltMV) virions’ thermal transition into structurally modified spherical particles (SP) has been demonstrated. The work has established differences in formation conditions of SP from virions (SP(V)) and VLPs (SP(VLP)) that are in accordance with structural data (on AltMV virions and VLPs). SP originate from AltMV virions through an intermediate stage. However, the same intermediate stage was not detected during AltMV VLPs’ structural remodelling. According to the biochemical analysis, AltMV SP(V) consist of protein and do not include RNA. The structural characterisation of AltMV SP(V/VLP) by circular dichroism, intrinsic fluorescence spectroscopy and thioflavin T fluorescence assay has been performed. AltMV SP(V/VLP) adsorption properties and the availability of chemically reactive surface amino acids have been analysed. The revealed characteristics of AltMV SP(V/VLP) indicate that they could be applied as protein platforms for target molecules presentation and for the design of functionally active complexes.