THE INVOLVEMENT OF MNN4 AND MNN6 MUTATIONS IN MANNOSYLPHOSPHORYLATIONOF O-LINKED OLIGOSACCHARIDE IN YEAST SACCHAROMYCES-CEREVISIAE

The structure of O-linked acidic oligosaccharide from Saccharomyces ce revisiae was analyzed. The chitinase, exclusively O-glycosylated extra celluar protein, was purified from strains mnn1, mnn1 mnn4, mnn1 mnn6 and Delta kre2 and the oligosaccharides were hydrolyzed by O-linked su gar chain specific hydrazinolysis. The mannosylphosphorylated mannotri ose (M3-P-M) was detected in strain mnn1, but not in the other three s trains (mnn1 (mnn4, mnn1 mnn6 and Delta kre2), alpha-Mannosidase treat ment and matrix-assisted laser desorption ionization time-of-flight ma ss spectrometry of mannosylphosphorylated mannotriose revealed that ma nnosylphosphate was attached to a middle mannose of alpha-1,2-linked m annotriose. This result indicates that the mnn4 and mnn6 mutations aff ect the mannosylphosphorylation of O-linked oligosaccharide, together with that of N-linked oligosaccharide. The amount of mannosylphosphory lated mannotriose was 7% of total O-linked oligosaccharides (20% of ne utral mannotriose) of chitinase in strain mnn1. (C) 1998 Elsevier Scie nce B.V. All rights reserved.