ИСТИНА

We replaced the CP gene of turnip vein cleaning tobamovirus (TVCV) by the mutant CP gene of Barley stripe mosaic hordeivirus (BSMV) with deletion of 22 Cterminal amino acid residues (TVCV ΔCCP BSMV). Previously we demonstrated that the infectious cDNA clone of the mutant chimeric virus agroinfiltrated into N.benthamiana plants efficiently accumulated in infected and systemic leaves. Here we studied the physicochemical characteristics of TVCV (ΔCCP BSMV) isolated from the systemic symptomatic leaves. The virus preparation was characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The TEM data demonstrated that the preparation contained a heterogeneous set of filamentous structures with width of 57 nm, variable in length forming network clusters of a weak electron density. Similar images were obtained by AFM. Measurement of the hydrodynamic diameter of TVCV (ΔCCP BSMV) particles by dynamic laser light scattering showed the presence of two peaks with sizes of about 100 nm and 800 nm indicating that the virus particles also form aggregates in the solution. However the removal of the Cterminal fragment of the CP BSMV does not significantly affect either the protein structure or its surface properties according the data of circular dichroism spectroscopy in the near ultraviolet range and the measurement of the surface zeta potential. It is known that the Cterminal disordered fragment of the CP is not involved in the formation of intersubunit interactions in the mature virion but we can not ruled out that it participates in the initial stages of the virion assembly. Our data indicate the importance of the integrity of the CP Cterminal region for the correct assembly of virions, and possibility of effective systemic transport of the tobamovirus genome in form of chimeric atypical virions (assumed ribonucleoprotein complexes). This work was supported by the Russian Science Foundation project No 142400007.