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Updated: May 16, 2026

Metabolic Glycoengineering of Sialic Acid Using N-acyl-modified Mannosamines
Published on: November 25, 2017
A bacterial glycosidase enables mannose-6-phosphate modification and improved cellular uptake of yeast-produced
Petra Tiels1, Ekaterina Baranova, Kathleen Piens
1Unit for Medical Biotechnology, Department for Molecular Biomedical Research, VIB, Ghent, Belgium.
Abstract:
Lysosomal storage diseases are treated with human lysosomal enzymes produced in mammalian cells. Such enzyme therapeutics contain relatively low levels of mannose-6-phosphate, which is required to target them to the lysosomes of patient cells. Here we describe a method for increasing mannose-6-phosphate modification of lysosomal enzymes produced in yeast. We identified a glycosidase from C. cellulans that 'uncaps' N-glycans modified by yeast-type mannose-Pi-6-mannose to generate mammalian-type N-glycans with a mannose-6-phosphate substitution. Determination of the crystal structure of this glycosidase provided insight into its substrate specificity. We used this uncapping enzyme together with α-mannosidase to produce in yeast a form of the Pompe disease enzyme α-glucosidase rich in mannose-6-phosphate. Compared with the currently used therapeutic version, this form of α-glucosidase was more efficiently taken up by fibroblasts from Pompe disease patients, and it more effectively reduced cardiac muscular glycogen storage in a mouse model of the disease.
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