Title : Expression of human interferon omega 1 in Sf9 cells
Abstract :
No evidence for complex-type N-linked glycosylation or sialylation
Human interferon omega 1 ( IFN-omega 1 ) was expressed in Spodoptera frugiperda Sf9 insect cells using the baculovirus expression system
Half of the protein purified by immunoaffinity chromatography was shown to be N-glycosylated at the same site as the natural IFN-omega 1
The degree of glycosylation was independent of the expression rate
While natural IFN-omega 1 was shown to carry complex-type oligosaccharides [Adolf, G. R., Maurer-Fogy, I., Kalsner, I. & Cantell, K. (1990) J. Biol
Chem
265, 9290-9295], the insect cell produced protein which was demonstrated by lectin blot, mass spectroscopy and HPLC analysis to contain only the core oligosaccharide
Two different structures, (Man)2(GlcNAc)2[Fuc] and (Man)3(GlcNAc)2[Fuc] were identified
The fucosylation was identified to be ( alpha 1-6 )-linked to the core saccharide
Sialic acid residues were clearly absent
IFN-omega 1 expressed in S. frugiperda cells was shown to be partially truncated at the C-terminus by nine residues; its antiviral activity when glycosylated was significantly lower than the activity of IFN-omega 1 produced by Sendai-virus-stimulated leukocytes
Circular dichroism and fluorescence spectroscopy did not reveal any structural differences between glycosylated and nonglycosylated IFN-omega 1
This implies the importance of a complex-type glycosylation for the maximal biological activity of human IFN-omega 1