A detailed analysis of the secondary structure has been carried out on the polygalacturonase-inhibiting protein (PGIP) from Phaseolus vulgaris, a leucine-rich repeat (LRR) protein present in the cell wall of many plants. Far-UV CD and infrared spectroscopies coupled to constrained secondary structure prediction methods indicated the presence of 12 alpha- and 12 beta-segments, thus allowing a schematic representation of three domains of the protein, namely, the central LRR region and the two cysteine-rich flanking domains. Peptides from endoproteinase-degraded PGIP were analyzed by mass spectrometry, and four disulfide bonds were identified. Mass spectrometric analysis in combination with glycosidase treatments revealed two N-linked oligosaccharides located on Asn 64 and Asn 141. The main structure resembled the typical complex plant N-glycan consisting of a core pentasaccharide beta1,2-xylosylated, carrying an alpha1,3-fucose linked to the innermost N-acetylglucosamine and one outer arm N-acetylglucosamine residue. The schematic representation of PGIP structural domains is discussed in the framework of the structure and function of LRR proteins.

Secondary Structure and Post-Translational Modifications of the Leucine-Rich Repeat Protein PGIP (Polygalacturonase-Inhibiting Protein) from Phaseolus vulgaris

MATTEI B;
2001

Abstract

A detailed analysis of the secondary structure has been carried out on the polygalacturonase-inhibiting protein (PGIP) from Phaseolus vulgaris, a leucine-rich repeat (LRR) protein present in the cell wall of many plants. Far-UV CD and infrared spectroscopies coupled to constrained secondary structure prediction methods indicated the presence of 12 alpha- and 12 beta-segments, thus allowing a schematic representation of three domains of the protein, namely, the central LRR region and the two cysteine-rich flanking domains. Peptides from endoproteinase-degraded PGIP were analyzed by mass spectrometry, and four disulfide bonds were identified. Mass spectrometric analysis in combination with glycosidase treatments revealed two N-linked oligosaccharides located on Asn 64 and Asn 141. The main structure resembled the typical complex plant N-glycan consisting of a core pentasaccharide beta1,2-xylosylated, carrying an alpha1,3-fucose linked to the innermost N-acetylglucosamine and one outer arm N-acetylglucosamine residue. The schematic representation of PGIP structural domains is discussed in the framework of the structure and function of LRR proteins.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11697/126441
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