Bondili Jayakumar Singh, Castilho Alexandra, Mach Lukas, Glössl Josef, Steinkellner Herta, Altmann Friedrich, Strasser Richard
Institute of Applied Genetics and Cell Biology, University of Natural Resources and Applied Life Sciences, BOKU-Vienna, Muthgasse 18, A-1190 Vienna, Austria.
Phytochemistry. 2006 Oct;67(20):2215-24. doi: 10.1016/j.phytochem.2006.07.007. Epub 2006 Aug 22.
Maize is considered a promising alternative production system for pharmaceutically relevant proteins. However, like in all other plant species asparagine-linked oligosaccharides of maize glycoproteins are modified with beta1,2-xylose and core alpha1,3-fucose sugar residues, which are considered to be immunogenic in mammals. This altered N-glycosylation when compared to mammalian cells may reduce the potential of maize as a production system for heterologous glycoproteins. Here we report the cloning and characterization of the cDNA sequences coding for the maize enzymes beta1,2-xylosyltransferase (XylT) and core alpha1,3-fucosyltransferase (FucT). The cloned XylT and FucT cDNAs were shown to encode enzymatically active proteins, which were independently able to convert a mammalian acceptor glycoprotein into an antigen binding anti-plant N-glycan antibodies. The complete sequence of the XylT gene was determined. Evidence for the presence of at least three XylT and FucT gene loci in the maize genome was obtained. The identification of the two enzymes and their genes will allow the targeted downregulation or even elimination of beta1,2-xylose and core alpha1,3-fucose addition to recombinant glycoproteins produced in maize.
玉米被认为是一种生产药用相关蛋白质的很有前景的替代生产系统。然而，与所有其他植物物种一样，玉米糖蛋白的天冬酰胺连接的寡糖被β1,2-木糖和核心α1,3-岩藻糖糖残基修饰，这些糖残基在哺乳动物中被认为具有免疫原性。与哺乳动物细胞相比，这种改变的N-糖基化可能会降低玉米作为异源糖蛋白生产系统的潜力。在此，我们报告了编码玉米β1,2-木糖基转移酶（XylT）和核心α1,3-岩藻糖基转移酶（FucT）的cDNA序列的克隆和表征。克隆的XylT和FucT cDNA显示编码具有酶活性的蛋白质，它们能够独立地将哺乳动物受体糖蛋白转化为与抗植物N-聚糖抗体结合的抗原。确定了XylT基因的完整序列。获得了玉米基因组中至少存在三个XylT和FucT基因座的证据。这两种酶及其基因的鉴定将使得能够有针对性地下调甚至消除玉米中产生的重组糖蛋白上β1,2-木糖和核心α1,3-岩藻糖的添加。
