The Aggregates of Vicilin Protein Are Found in the Roots and Nodules of Pisum sativum L.

Abstract

Amyloids are unbranched protein fibrils with a characteristic spatial structure and unusual features including high resistance to detergent or protease treatment. Numerous investigations of amyloids are of the top interest due to the increasing incidence of amyloid-associated disorders, for instance, Alzheimer's disease, Parkinson's disease, type II diabetes, and also due to functional roles of amyloids in prokaryotes and eukaryotes. Previously, for the first time, we have found that 47 kDa Vicilin, belonging to the 7S globulin storage protein group, form amyloids in plant seeds (Antonets et al., PLOS Biology, 2020). In this work, using previously obtained polyclonal antibody, we studied the production of the Vicilin protein in various parts of the garden pea (Pisum sativum L.) plants. According to the results of western blot hybridization, Vicilin was found in all observed organs of the pea (leaves, tendrils, shoots, roots and nodules), but its amount was much higher in the roots and nodules, and there was also found an aggregated fraction of this protein. In vivo, histological analysis of pea plant organs cryosections showed the presence of Vicilin in roots as well as in nodules, which, combined with western blot results allows us to presume that all or some of it is in an aggregate form. These findings let us hypothesize that aggregated Vicilin is involved in the supra-organismal interactions between P. sativum L. and symbiotic bacteria.