N-Glycosylation in Chrysosporium lucknowense enzymes

Twenty-eight enzymes, encoded by different genes and secreted by different mutant strains of Chrysosporium lucknowense, were subjected to MALDI-TOF MS peptide fingerprinting followed by analysis of the MS data using the GlycoMod tool from the ExPASy proteomic site. Various N-linked glycan structures were discriminated in the C. lucknowense proteins as a result of the analysis. N-Glycosylated peptides with modifications matching the oligosaccharide compositions contained in the GlycoSuiteDB were found in 12 proteins. The most frequently encountered N-linked glycan, found in 9 peptides from 7 proteins, was (Man)(3)(GlcNAc)(2), that is, the core pentasaccharide structure forming mammalian-type high-mannose and hybrid/complex glycans in glycoproteins from different organisms. Nine out of 12 enzymes represented variably N-glycosylated proteins carrying common (Hex)(0-4)(HexNAc)(0-6)+(Man)(3)(GlcNAc)(2) structures, most of them being hybrid/complex glycans. Various glycan structures were likely formed as a result of the enzymatic trimming of a 'parent' oligosaccharide with different glycosidases. The N-glycosylation patterns found in C. lucknowense proteins differ from those reported for the extensively studied enzymes from Aspergilli and Trichoderma species, where high-mannose glycans of variable structure have been detected.