Oligomerization of the reversibly glycosylated polypeptide: its role during rice plant development and in the regulation of self-glycosylation

DE PINO V,; MARINO BUSJLE C; MORENO S

PROTOPLASMA

SPRINGER WIEN

Lugar: Viena; Año: 2011

0033-183X

polypeptides designated as RGPs, have been usually associated with carbohydrate metabolism, although they are an enigma both at the functional, as well as at the structural level. In this work, we used biochemical approaches to demonstrate that complex formation is linked to rice plant development, in which class 1 Oryza sativa RGP (OsRGP) would be involved in an early stage of growing plants, while class 2 OsRGP would be associated with a late stage associated with an active polysaccharide synthesis that occurs during the elongation of plant. Here, a further investigation of the complex formation of the Solanum tuberosum RGP (StRGP) was performed. Results showed that disulphide bonds are at least partially responsible for maintaining the oligomeric protein structure, so that the non-reduced StRGP protein showed an apparent higher molecular weight and a lower radioglycosylation of the monomer with respect to its reduced form. Hydrophobic-cluster analysis and secondary structure prediction revealed that class 2 RGPs no longer maintained the Rossman fold described for class 1 RGP. A 3D structure of the StRGP protein resolved by homology modeling supports the possibility of intercatenary disulphide bridges formed by exposed cysteines residues C79, C303 and C251 and they are most probably involved in complex formation occurring into the cell cytoplasm.