OBJECTIVE The FLT-3 ligand （fms-like tyrosine kinase receptor-3 ligand, FL） is a recently described growth factor affecting early hematopoietic progenitor cells. The FL plays a key role in the growth and differentia...OBJECTIVE The FLT-3 ligand （fms-like tyrosine kinase receptor-3 ligand, FL） is a recently described growth factor affecting early hematopoietic progenitor cells. The FL plays a key role in the growth and differentiation of primitive hematopoietic cells. To yield a high-level of recombinant human FL protein, a recembinant Pichia Pastoris （P. pastoris）strain was constructed. METHODS An artificial expression frame, with the same encoding protein sequence for the FL extracellular domain cDNA, was synthesized by using favored genetic codons of P. pastoris. P. pastoris strain KM71 cells were transformed with the endonuclease Bgl II linearized recombined plasmid, pPIC9K-FL. The plasmid then was linerized in the 5＇AOX1 site and integrated into the yeast KM71 genome. KM71 was transformed with pPIC9K plasmids as a control for the production of recombinant protein. Southern blotting and Northern blotting tests were used to screen the genotype of the recombined strain. Biological activity was demonstrated in vitro with culturing of CD34＋cells. RESULTS The recombinant human FL protein expressed into the yeast culture supertant was identified on the basis of its molecular weight and Western blotting analysis. Numerous bands were observed in the 10-100 kDa molecular mass range. SDS-PAGE showed that the expressed product, a 20 kDa protein, was secreted into the medium in the form of a soluble molecule. Western-blot analyses showed good antigenicity and specificity against polyclonal antibodies. A sharp band and a smeared band were observed at a molecular mass of approximately 20 kDa by Western blotting. The recombinant human FL protein was the major protein component observed in the culture supernatant. The highest yield （108 mg/L） was obtained when expression was induced with 0.5% methanol for 96 h. Deglycosylation with PNGase F resulted in a decrease in apparent molecular mass from 20 kDa to 18kDa forming three bands all of which were also detected by rabbit anti-FL antibodies, Culturing of CD34＋ cells in the presence of KM71pPIC9K-FL over 7 days increased 2.9 fold, while in the control group they increased only 1,5 fold. The biological assay showed that the expressed product could stimulate the proliferation of CD34＋ hematopoietic cells, CONCLUSION We demonstrated that human FL was secreted into the culture supernatant from P. pastoris, and that this yeast strain was a preferred host for recombinant human FL gene expression. This recombinant strain can provide a convenient process for pharmaceutical application.展开更多
The gene of human thymosin alpha 1(hT(1)was synthesised according to favorite codons of Pichia pastoris by PCR. N-terminal 28 amino acid residues of 40S ribosomal protein (RP), S24E that is N-acetylserine were replace...The gene of human thymosin alpha 1(hT(1)was synthesised according to favorite codons of Pichia pastoris by PCR. N-terminal 28 amino acid residues of 40S ribosomal protein (RP), S24E that is N-acetylserine were replaced by hT(1 for the constitution of hT(1-RP fusion gene in order to express acetyllated thymosin α 1. And also,the Asn-Gly bond was designed to faciliate isolation of the target protein.The fusion gene was cloned into the expression vector, pPIC/9K. The constructs were transformed into HIS4 mutant strain GS115 by electroporation. Both SDS-PAGE analysis and Western blot analysis indicated that the fusion protein was expressed successfully.展开更多
The present study was designed to determine the effects of copy number variations(CNVs) of squalene synthase 1(SQS1) gene on the mevalonate(MVA) pathway.SQS1 gene from G.uralensis(Gu SQS1) was cloned and over-expresse...The present study was designed to determine the effects of copy number variations(CNVs) of squalene synthase 1(SQS1) gene on the mevalonate(MVA) pathway.SQS1 gene from G.uralensis(Gu SQS1) was cloned and over-expressed in Pichia pastoris GS115.Six recombinant P.pastoris strains containing different copy number of Gu SQS1 were constructed.HPLC was used to assay the level of ergosterol in all transgenic P.pastoris strains containing Gu SQS1.HPLC analysis showed that the contents of ergosterol in all of the transgenic P.pastoris containing Gu SQS1 were higher than that in the negative control.And with the increase of copy number of Gu SQS1,the content of ergosterol showed an increasing-decreasing-increasing pattern.The contents of ergosterol in 10-copy-Gu SQS1 P.pastoris and 47-copy-Gu SQS1 P.pastoris were significantly higher than that in the rest recombinant P.pastoris strains.In conclusion,the CNVs of Gu SQS1 influence the content of secondary metabolites in the MVA pathway.The present study provides a basis for over-expressing Gu SQS1 and increasing the content of glycyrrhizin in G.uralensis cultivars.展开更多
文摘OBJECTIVE The FLT-3 ligand （fms-like tyrosine kinase receptor-3 ligand, FL） is a recently described growth factor affecting early hematopoietic progenitor cells. The FL plays a key role in the growth and differentiation of primitive hematopoietic cells. To yield a high-level of recombinant human FL protein, a recembinant Pichia Pastoris （P. pastoris）strain was constructed. METHODS An artificial expression frame, with the same encoding protein sequence for the FL extracellular domain cDNA, was synthesized by using favored genetic codons of P. pastoris. P. pastoris strain KM71 cells were transformed with the endonuclease Bgl II linearized recombined plasmid, pPIC9K-FL. The plasmid then was linerized in the 5＇AOX1 site and integrated into the yeast KM71 genome. KM71 was transformed with pPIC9K plasmids as a control for the production of recombinant protein. Southern blotting and Northern blotting tests were used to screen the genotype of the recombined strain. Biological activity was demonstrated in vitro with culturing of CD34＋cells. RESULTS The recombinant human FL protein expressed into the yeast culture supertant was identified on the basis of its molecular weight and Western blotting analysis. Numerous bands were observed in the 10-100 kDa molecular mass range. SDS-PAGE showed that the expressed product, a 20 kDa protein, was secreted into the medium in the form of a soluble molecule. Western-blot analyses showed good antigenicity and specificity against polyclonal antibodies. A sharp band and a smeared band were observed at a molecular mass of approximately 20 kDa by Western blotting. The recombinant human FL protein was the major protein component observed in the culture supernatant. The highest yield （108 mg/L） was obtained when expression was induced with 0.5% methanol for 96 h. Deglycosylation with PNGase F resulted in a decrease in apparent molecular mass from 20 kDa to 18kDa forming three bands all of which were also detected by rabbit anti-FL antibodies, Culturing of CD34＋ cells in the presence of KM71pPIC9K-FL over 7 days increased 2.9 fold, while in the control group they increased only 1,5 fold. The biological assay showed that the expressed product could stimulate the proliferation of CD34＋ hematopoietic cells, CONCLUSION We demonstrated that human FL was secreted into the culture supernatant from P. pastoris, and that this yeast strain was a preferred host for recombinant human FL gene expression. This recombinant strain can provide a convenient process for pharmaceutical application.
文摘The gene of human thymosin alpha 1(hT(1)was synthesised according to favorite codons of Pichia pastoris by PCR. N-terminal 28 amino acid residues of 40S ribosomal protein (RP), S24E that is N-acetylserine were replaced by hT(1 for the constitution of hT(1-RP fusion gene in order to express acetyllated thymosin α 1. And also,the Asn-Gly bond was designed to faciliate isolation of the target protein.The fusion gene was cloned into the expression vector, pPIC/9K. The constructs were transformed into HIS4 mutant strain GS115 by electroporation. Both SDS-PAGE analysis and Western blot analysis indicated that the fusion protein was expressed successfully.
基金supported by National Natural Science Fundation of China(No.81373909)
文摘The present study was designed to determine the effects of copy number variations(CNVs) of squalene synthase 1(SQS1) gene on the mevalonate(MVA) pathway.SQS1 gene from G.uralensis(Gu SQS1) was cloned and over-expressed in Pichia pastoris GS115.Six recombinant P.pastoris strains containing different copy number of Gu SQS1 were constructed.HPLC was used to assay the level of ergosterol in all transgenic P.pastoris strains containing Gu SQS1.HPLC analysis showed that the contents of ergosterol in all of the transgenic P.pastoris containing Gu SQS1 were higher than that in the negative control.And with the increase of copy number of Gu SQS1,the content of ergosterol showed an increasing-decreasing-increasing pattern.The contents of ergosterol in 10-copy-Gu SQS1 P.pastoris and 47-copy-Gu SQS1 P.pastoris were significantly higher than that in the rest recombinant P.pastoris strains.In conclusion,the CNVs of Gu SQS1 influence the content of secondary metabolites in the MVA pathway.The present study provides a basis for over-expressing Gu SQS1 and increasing the content of glycyrrhizin in G.uralensis cultivars.
