Complex formation regulates the glycosylation of the reversibly glycosylated polypeptide |
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Authors: | Verónica De Pino Mariela Borán Lorena Norambuena Mariela González Francisca Reyes Ariel Orellana Silvia Moreno |
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Institution: | (1) Plant Biochemistry Laboratory, Instituto de Investigaciones Bioquímicas, Fundación Instituto Leloir, formerly “Fundación Campomar”, I.I.B.B.A. Patricias Argentinas 435, Capital Federal, 1405, Argentina;(2) Millennium Nucleus in Plant Cell Biology and Center of Plant Biotechnology, Andrés Bello University, República 217, Santiago, Chile;(3) Present address: Center for Plant Cell Biology, Department of Botany and Plant Sciences, University of California Riverside, 2130 Batchelor Hall, Riverside, CA 92521, USA |
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Abstract: | Reversible glycosylated polypeptides (RGPs) are highly conserved plant-specific proteins, which can perform self-glycosylation.
These proteins have been shown essential in plants yet its precise function remains unknown. In order to understand the function
of this self-glycosylating polypeptide, it is important to establish what factors are involved in the regulation of the RGP
activity. Here we show that incubation at high ionic strength produced a high self-glycosylation level and a high glycosylation
reversibility of RGP from Solanum tuberosum L. In contrast, incubation at low ionic strength led to a low level of glycosylation and a low glycosylation reversibility
of RGP. The incubation at low ionic strength favored the formation of high molecular weight RGP-containing forms, whereas
incubation at high ionic strength produced active RGP with a molecular weight similar to the one expected for the monomer.
Our data also showed that glycosylation of RGP, in its monomeric form, was highly reversible, whereas, a low reversibility
of the protein glycosylation was observed when RGP was part of high molecular weight structures. In addition, glycosylation
of RGP increased the occurrence of non-monomeric RGP-containing forms, suggesting that glycosylation may favor multimer formation.
Finally, our results indicated that RGP from Arabidopsis thaliana and Pisum sativum are associated to golgi membranes, as part of protein complexes. A model for the regulation of the RGP activity and its binding
to golgi membranes based on the glycosylation of the protein is proposed where the sugars linked to oligomeric form of RGP
in the golgi may be transferred to acceptors involved in polysaccharide biosynthesis. |
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Keywords: | Golgi Plant polysaccharides Reversibly glycosylated polypeptide Self-glycosylation Xyloglucan |
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