Secondary structure and post-translational modifications of the leucine-rich repeat protein PGIP (polygalacturonase-inhibiting protein) from Phaseolus vulgaris.
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.
Mattei
B
B
Dipartimento di Biologia Vegetale, Universitá di Roma "La Sapienza", Piazzale Aldo Moro 5, 00185 Roma, Italy.
Bernalda
M S
MS
Federici
L
L
Roepstorff
P
P
Cervone
F
F
Boffi
A
A
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004220:Disulfides / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000378:metabolism*; D007887:Fabaceae; D006031:Glycosylation; D007930:Leucine / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism*; D010946:Plants, Medicinal; D011096:Polygalacturonase / Q000037:antagonists & inhibitors*; D011499:Protein Processing, Post-Translational; D017433:Protein Structure, Secondary; D020449:Repetitive Sequences, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D017550:Spectroscopy, Fourier Transform Infrared
D004220:Disulfides; D004791:Enzyme Inhibitors; C081479:PGIP protein, plant; D010940:Plant Proteins; D011096:Polygalacturonase; D007930:Leucine