Glyco-Design at Golgi membranes

Prof. Dr. Ralf Reski (Plant Biotechnology, University of Freiburg)

We established the moss Physcomitrella patens as an alternative production host for recombinant biopharmaceuticals. Here we will further improve this system towards humanisation of its protein N-glycosylation. This will be achieved by glyco-design, especially by preventing the activity of endogenous plant-specific glycosyltransferases combined with the introduction of the respective human enzymes that are absent from plants. The modification of the plant N-glycosylation pathway will lead to the abolishment of putatively allergenic plant-specific sugar residues, increased in vivo activity and serum half-life of the biopharmaceuticals produced in the moss bioreactor.

Part of this project is the reconstitution of the human sialylation pathway within the moss, via design of synthetic chimeric enzymes, which combine human catalytic activity and plant Golgi membrane localisation domains. It is known that enzymes of the human glycosylation pathway are functional in plants. However, in their native form they could act in a wrong sequential order, sometimes caused by mislocalization within the Golgi sub-compartments. The correct organisation of the glycosylation enzymes in the sequential signalling network within the Golgi apparatus is necessary and will be analysed by advanced microscopy and subcellular localization. The function within the N-glycosylation sequence will be examined via MS of target protein glycan patterns.