N-Glycosylation Humanization for Production of Therapeutic Recombinant Glycoproteins in Saccharomyces cerevisiae

The production of therapeutic recombinant glycoproteins deals with three main issues: cost, production capacities, and glycosylation. Nowadays, such proteins are expressed in various complex expression systems (CHO, bacteria, etc.); the processes related to those production hosts are time consuming and expensive, or the question of posttranslational modifications (as glycosylation) control is still unresolved. There is a need to find an alternative approach, while maintaining high quality level: the new system must be able to add complex N -glycan structures to proteins of interest. Developed in several strains of Saccharomyces cerevisiae , GlycodExpress™ is an innovative technology that allows production of therapeutic recombinant glycoproteins with humanized and homogeneous N -glycan moieties. We show how to delete mannosyltransferases involved in host N-glycosylation to obtain more than 90% of homogeneity in glycan structures. The methodology developed to select the optimal fusion between a heterologous glycosyl-enzyme and a localization sequences is also presented. Finally, the screening of the best producing strain is illustrated.