ABSTRACT
Objective To obtain a strain of glycoengineering yeast with higher N-glycosylation efficiency by overexpressing N-glycosyltransferase.Methods Through the selecting marker URA3 gene, a new glycoengineering yeast strain named 4-32-STT3D was constructed, which could overexpress the Leishmania major N-glycosyltransferase staurosporine and temperature sensitivity3 D subunit(STT3D) under the control of an inducible alcohol oxidase 1(AOX1) promoter.We analyzed the N-glycosylation status of anti-human epidermal growth factor receptor 2 ( HER2 ) antibody and granulocyte macrophage colony stimulating factor (GM-CSF) expressed in 4-32-STT3D using SDS-PAGE,Western blotting and peptide-N-asparigineamidase F(PNGase F).Finally the effect of STT3D on the growth rate of glycoengineering yeast was detected.Results SDS-PAGE showed that anti-HER2 antibody expressed in 4-32-HL had two components:the first one with a relative molecular mass 55 ×103 was glycosylated,while the second one with 50 ×103 was non-glycosylated,but anti-HER2 antibody expressed in 4-32-HL-STT3D had the component of 55 ×103 only without any non-glycosylated 50 ×103 .The above components became 50 ×103 with the digestion of PNGaseF.All of them proved to be antibodies by Western blotting.As a report protein,GM-CSF expressed in 4-32-GM-CSF had two components: 22 ×103 and 20 ×103, while in 4-32-GM-CSF-STT3D there was only one with 22 ×103 .All these components became 18 ×103 with the digestion of PNGase F.Statistical analysis showed that without induction,STT3D had no effect on the growth rate of glycoengineering yeast, while great effect was observed when STT3D was induced.Conclusion Glycoengineering yeast with the overexpression of N-glycosyltransferase has higher N-glycosylation efficiency.
ABSTRACT
Objective To develop an interleukin-4(IL-4) antagonist named M5-IgG1Fc protein constructed by genetic engineering of antibody Fc fragment-cytokine mutein fusion protein which has a long half-life time in plasma.M5-IgG1 Fc protein binds to IL-4 receptor but cannot activate downstream signalling pathway , which provides a basis for drug develop-ment for allergic diseases .Methods The synthesized interleukin-4 mutant gene ( named M5 ) was cloned into the expres-sion vector pBV220 and transformed into E.coli DH5α.Chimeric gene M5-IgG1Fc obtained by overlap extension (SOE) method was transformed into glycoengineered Pichia pastoris GJK01 through expression vector pPICZαA .Then M5-IgGFc fusion protein was obtained by protein purification after being induced by methanol in 72 hours.The anti-IL-4 biologicial ac-tivity assay of M5 and M5-IgG1 Fc was performed with CTLL-2/IL-4R cells and detected with MTT colormetry .Finally,the half-life time of M5 and M5-IgG1 Fc protein in mice was compared by detecting the remaining amount in plasma with ELISA kit.Results The M5 protein expressed in E.coli and M5-IgG1 Fc fusion protein expressed in P.pastoris GJK01 both had IL-4 antagonistic bioactivity .The EC50 of both, which inhibited 5.6 ×10 -2 nmol/ml of IL-4, were 0.31 ±0.05 and 0.77 ± 0.03 nmol/ml,respectively.The maximum of M5 in plasma at 0.5 h was 5.8 ×10 -2 nmol/ml but the remaining amount was 2.8%of the maximum at 2 h.M5 protein could not be detected after administration at 8 h because of the detection line . The maximum of M5-IgG1 Fc fusion protein was 4.7 ×10 -2 nmol/ml,while fusion protein M5-IgG1 Fc decreased to 4.3%of its maximum at 120 h and could not be detected at 168 h.Conclusion M5 protein has IL-4 antagonistic bioactivity .M5-IgG1 Fc fusion protein expressed in glycoengineered P.pastoris GJK01 has IL-4 antagonistic bioactivity and long retention time in mice,which can be potentially used for treatment of allergic diseases .
ABSTRACT
Objective To prepare endo-beta-N-acetylglucosaminidase H (Endo-H) expressed in Pichia pastoris, and apply it to N-glycosylation analysis .Methods One complete gene was synthesized on the basis of the cDNA sequence encoding Streptomyces plicatus reported in GenBank .The gene was cloned into the expression vector pPIC 9.The expression vector pPIC9-Endo-H was transformed into P.pastoris(JC308).The expression products were induced by methanol , puri-fied by two-step chromatography , used to analyze the glycan structures of RNaseB by the DNA sequencer assisted fluoro-phore-assisted carbohydrate electrophoresis (DSA-FACE)methods, and finally compared with peptide-N-asparagine amidase F(PNGase F).Results This enzyme expressed in P.pastoris(JC308) had the ability to hydrolyze natural or denatured high-mannose type of oligosaccharide linked by β-1,4-glycosidic bonds , but not complex-type oligosaccharide .The result of DSA-FACE showed that carbohydrate chains of Man 5 GlcNAc-Man9 GlcNAc could be obtained when RNaseB was hydrolyzed by Endo-H, and that Man5 GlcNAc2-Man9 GlcNAc2 chains became available when RNaseB was hydrolyzed by PNGase F . Conclusion Endo-H expressed in P.pastoris has bioactivity which can be used to analyze N-glycosylation with the method of DSA-FACE.