Structural and Functional Characterization of Reversibly Glycosylated Polypeptide of Guar Involved in Cell Wall Polysaccharide Metabolism

 

Reversible glycosylated polypeptides (RGPs) are highly conserved plant-specific proteins, which can auto-glycosylate. RGPs are essential for plants yet its precise function remains unknown. Genomic, proteomic and immunocytochemical localization data indicate that RGP protein is involved in a variety of metabolic and developmental pathways in plants. This is a membrane peripheral protein found in association with the trans-Golgi cisternae. In guar, this protein, consisting of 353 amino acids, is believed to be responsible for the biosynthesis of hemicellulosic polysaccharide that constitutes cell wall. In this study, cloning, sequencing and heterologous expression were done experimentally.  Structural and functional characterization of this protein sequence was carried out by using different bioinformatics tools. The results showed that this is a stable, active and folded polypeptide belongs to RGP superfamily. The three dimensional structure was generated by 3D modeling with Thread software and validated by docking with its specific substrates i.e. UDP-Glucose and UDP-galactose.  Structural analysis of this protein by crystallography is still in progress, which will serve as the first example of crystal structure of any RGP superfamily.

T