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Post‐translational modifications of recombinant B. cinerea EPG 6
Author(s) -
Xie Min,
Krooshof Geja H.,
Benen Jacques A. E.,
Atwood James. A.,
King Daniel,
Bergmann Carl,
Orlando Ron
Publication year - 2005
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.2194
Subject(s) - chemistry , glycosylation , peptide , glycan , oligosaccharide , n linked glycosylation , glycoprotein , biochemistry , matrix assisted laser desorption/ionization , chromatography , organic chemistry , adsorption , desorption
The fungus Botrytis cinerea is a ubiquitous plant pathogen that infects more than 200 different plant species and causes substantial economic losses in a wide range of agricultural crops and harvested products. Endopolygalacturonases (EPGs) are among the first array of cell‐wall‐degrading enzymes secreted by fungi during infection. Up to 13 EPG glycoforms have been described for B. cinerea . The presence of multiple N ‐linked glycosylation modifications in BcPG1‐6 is predicted by their deduced amino acid sequences. In this work, the glycosylation sites and the attached oligosaccharide structures on BcPG6 were analyzed. The molecular mass of the intact glycoprotein was determined by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometric (MALDI‐TOFMS) analysis. BcPG6 contains seven potential N ‐linked glycosylation sites. Occupancy of these glycosylation sites and the attached carbohydrate structures were analyzed by tryptic digestion followed by liquid chromatography/mass spectrometry (LC/MS) using a stepped orifice voltage approach. Five out of seven potential N ‐linked sites present in BcPG6 were determined to be occupied by high‐mannose‐type oligosaccharides. Four of them were readily determined to be at Asn 58 (T3 peptide), Asn 198 (T7 peptide), Asn 237 (T9 peptide) and Asn 256 (T11 peptide), respectively. Another was located on the T8 peptide, which contained two potential N ‐linked sites, Asn 224 and Asn 227 (SNN N 224 VT N 227 ITFK). LC/MS/MS of a sample treated with N ‐glycanase placed the glycan in this peptide at Asn 224 rather than at Asn 227 . The potential glycosylation site on Asn 146 (T6 peptide) was not glycosylated. In addition, two disulfide bonds were observed, linking the Cys residues within the T13 and T16 peptides. Copyright © 2005 John Wiley & Sons, Ltd.