Caracterización de las formas de alto peso molecular de la proteína RGP (Reversibly Glycosylated Polypeptide)

VERÓNICA DE PINO; DIEGO GRINMAN; SILVIA MORENO

Villa Carlos Paz, Cordoba, Argentina

Congreso; XLIV Reunion Anual-Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular; 2008

SAIB

PL-C05.CHARACTERIZATION OF HIGH MOLECULAR FORMSOF THE REVERSIBLE GLYCOSYLATED POLYPEPTIDEDePino V, Grinman D, Moreno S.Fundación Instituto Leloir, IIBBA-CONICET. E-mail:VDePino@leloir.org.arReversible glycosylated polypeptides (RGPs) are highlyconserved plant specific proteins. They perform self-glycosylationusing uridine sugars as substrate. Its precise function remainsunknown. To establish what factors are involved in the regulationof the RGP activity, we studied the relation betweenoligomerization and activity. We already published a model for theregulation of the RGP activity involving the occurrence of RGPcomplexes and the correlation with a decreased ability of thosecomplexes to release glucose to UDP. Here, we found that complexformation depends on the plant development stage. Thesecomplexes are partially stabilized by disulfide bonds and thereduction of these bonds modulates the size and the activity of theprotein. In addition, different native forms differing in chargeand/or in size are visualized after Mono Q or Superose 12chromatography, respectively. When the more active fractionseluted from Mono Q column was purified by UDP-hexanolamineAgarose, the pure RGP protein showed a complex UV spectrumsignal, compatible with an interaction of the manganese, used as acofactor of the RGP, with the UDP. To summarize, all data suggestthat the behavior exhibited by RGP is quite unique and it canprovide us a clue regarding to the function involved inpolysaccharide biosynthesis in plants.