O-Glycan analysis of cellobiohydrolase I from Neurospora crassa.

We describe here the composition of the O-linked glycans on the Neurospora crassa cellobiohydrolase I (CBHI), which accounts for approximately 40% of the protein secreted by cells growing in the presence of cellulose. CBHI is O-glycosylated with six types of linear, and three types of branched, O-glycans containing approximately equal amounts of mannose and galactose. In addition to the classic fungal O-glycans with reducing end mannoses, we also identified reducing end galactoses which suggest the existence of a protein-O-galactosyltransferase in N. crassa Because of the excellent genetic resources available for N. crassa, the knowledge of the CBHI O-glycans may enable the future evaluation of the role of O-glycosylation on cellulase function and the development of directed O-glycan/cellulase engineering.