GLYCOSYLATION ENGINEERING: CHO MUTANTS FOR THE PRODUCTION OF GLYCOPROTEINS WITH TAILORED CARBOHYDRATES

Abstract

Most glycoproteins require their carbohydrates in order to be synthesized efficiently and in a biologically active, stable form. However it is clear that the actual structures of these carbohydrates can vary widely; severly truncated forms will often confer the desired characteristics. Minimizing carbohydrate heterogeneity may be advantageous for many reasons, especially in the production of recombinant glycocoproteins. To obtain glycoproteins with a limited set of carbohydrate structures glycosylation mutants with mutations in carbohydrate biosynthesis can be used. Chinese hamster ovary (CHO) glycosylation mutants that are missing an enzyme activity (e.g. a transferase or translocase) synthesize truncated carbohydrates with predictable structures. For purification or tissue-targeting purposes, it may be desirable to embellish carbohydrates with particular sugar residues. Dominant CHO mutants or CHO cells transfected with a cloned glycosyltransferase can be used for this purpose. Most of the CHO mutants that synthesize altered carbohydrates grow well in culture showing that a wide range of carbohydrate structures are compatible with viability. These lines can readily be used to engineer the carbohyrates of recombinant glycoproteins for a multitude of purposes.