Seed storage globulins: origin and evolution of primary and higher order structures

• Published in: Biochemistry (Moscow) 2015-10, p.1354
• Main Authors: Rudakova, A.S, Cherdivara, A.M, Wilson, K.A, Shutov, A.D
• Format: Article
• Language: English
• Subjects: Globulin; Health aspects; Observations; Protein-protein interactions
• ISSN: 0006-2979
• DOI: 10.1134/S000629791510017

Legumin and vicilin are two-domain seed storage globulins similar in primary and higher order structures of their domains to single-domain plant germins as well as to the domains of two-domain and single-domain bacterial oxalate decarboxylases. Independent evolutionary pathways have been shown for the descent of the storage globulins and germins from two-domain and single-domain bacterial oxalate decarboxylases, respectively. As compared to vicilins, the primary and tertiary structures of legumins were found to most closely reflect the ancient features characteristic of a common precursor of storage globulins. During the evolution of the storage globulins, a mechanism specifically controlling their degradation has been formed. We found that limited proteolysis of soybean legumin and kidney bean vicilin in germinating seeds and in vitro leads to their regular changes, which initiate an extensive cleavage of storage globulin molecules by the one-by-one mechanism. As also shown, limited proteolysis of soybean legumin loosens the intersubunit interactions in its oligomeric molecule. Based on these data, we hypothesize that the deep one-by-one degradation of soybean legumin is triggered by its dissociation, which bares peptide bonds potentially susceptible to proteolytic attack but are masked in the oligomer. DOI: 10.1134/S000629791510017 Key words: seed storage globulins, germins, oxalate decarboxylases, tertiary structure, volution, proteolysis