title: Targeted knockouts of Physcomitrella lacking plant-specific immunogenic N-glycans.
abstract: Using plants as production factories for therapeutic proteins requires modification of their N-glycosylation pattern because of the immunogenicity of plant-specific sugar residues. In an attempt towards such humanization, we disrupted the genes for alpha1,3-fucosyltransferase and beta1,2-xylosyltransferase in Physcomitrella patens by homologous recombination. The single Deltafuc-t and Deltaxyl-t plants, as well as the double knockout, lacked transcripts of the corresponding genes, but did not differ from the wild-type moss in morphology, growth, development, and ability to secrete a recombinant protein, the human vascular endothelial growth factor VEGF(121), into the culture medium. N-Glycan analysis, however, revealed the absence of 1,3-fucosyl and/or 1,2-xylosyl residues, respectively. Therefore, the modifications described here represent the key step towards the generation of moss lines suitable for the production of plant-made glycosylated biopharmaceuticals with nonallergenic N-glycans.
authors.affiliation: University of Freiburg, Plant Biotechnology, Schaenzlestr. 1, 79104 Freiburg, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Koprivova
authors.forename: Christian
authors.initials: C
authors.lastname: Stemmer
authors.forename: Friedrich
authors.initials: F
authors.lastname: Altmann
authors.forename: Axel
authors.initials: A
authors.lastname: Hoffmann
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kopriva
authors.forename: Gilbert
authors.initials: G
authors.lastname: Gorr
authors.forename: Ralf
authors.initials: R
authors.lastname: Reski
authors.forename: Eva L
authors.initials: EL
authors.lastname: Decker