Hepatitis E is an enterically transmitted viral disease caused by infection with hepatitis E virus（HEV）. HEV is a nonenveloped virus that bas been classified in the family of Caliciviridae. The virus appears to be a...Hepatitis E is an enterically transmitted viral disease caused by infection with hepatitis E virus（HEV）. HEV is a nonenveloped virus that bas been classified in the family of Caliciviridae. The virus appears to be a polya-denylated, positive-stranded RNA virus with three major open reading frames（ORFs）. The capsid protein of HEV is encoded by the open reading frame 2（ORF2）. We attempted to produce a truncated capsid protein, designed p293, in Pichia pastoris. The p293 gene encoding amino acids（aa） 382-674 of HEV ORF2 was designed based on the full length of HEV ORF2, cloned into the yeast vector pPIC9K, and expressed in P. pastoris strain GS 115. SDS-PAGE and Western blotting demonstrated that the recombinant protein p293 could well be expressed in P pastoris. Under optimized conditions （culture medium pH, 6.0-6.5; methanol concentration added daily, 3.0%; inoculum density, OD600=60; induction time point, 72-96 h）, the yield of soluble p293 was approximately 80 mg/L. We also observed p293 secretory expressed in P. pastoris to be 30 nm viral like particles by using electron microscopy. These results show that the p293 may has utility in the analysis of cell specific factors in the protein processing and assembly of HEV, and serve as a useful antigen for both diagnostic and vaccine purposes.展开更多
Mammalian cells express two isoforms of Cu- and Zn-containing superoxide dismutases（SODs）, CuZn-SOD and extracellular SOD（EC-SOD）, involved in the defense system against reactive oxygen species（ROS）. The two SOD...Mammalian cells express two isoforms of Cu- and Zn-containing superoxide dismutases（SODs）, CuZn-SOD and extracellular SOD（EC-SOD）, involved in the defense system against reactive oxygen species（ROS）. The two SODs have structurally homologous centre domain with distinct N- and C-terminuses, resulting in the different characteristics of the structure and function of the two molecules. We generated a hybrid SOD molecule（namely hy- SOD） via replacing the N- and C-terminuses of hCuZnSOD with the counterparts of hEC-SOD. The hySOD was expressed in host Pichia pastoris and the purified protein was a dimer with a molecular weight of about 34000. A series of activity analyses indicates that the hySOD is similar to hEC-SOD in heat-stability, and has the activity of protecting the host cell against heat shock and oxidative stress. Our results show evidence for the study on the compound activity of multiple SOD molecules, and may be important for understanding the relationship between structure and function of hEC-SOD and hCuZnSOD.展开更多
β-Mannanase catalyzes endo-wise hydrolysis of the backbone of mannan and heteromannan,which are abun-dant in the cell wall structure of ungerminated leguminous seeds.The mature β-mannanase originated from Bacillus s...β-Mannanase catalyzes endo-wise hydrolysis of the backbone of mannan and heteromannan,which are abun-dant in the cell wall structure of ungerminated leguminous seeds.The mature β-mannanase originated from Bacillus subtilis was expressed in Pichia pastoris,a methylotrophic yeast,using the leader peptide sequence of Saccharomyces cerevisiae α-factor.The cultivation of β-mannanase express-ing Pichia pastoris yields up to 1.8 g/L protein.In the super-natant the activity of the 40 kDa—total mannanase attained a level of 1102.0 IU/mL.The properties of the β-mannanase were characterized.Optimum pH and temperature for the recombinant enzyme were 5.5 and 50℃ respectively.The enzyme was stable at pH 5.0-10.0 and maintained over 30%original activity after incubating at 70℃ for 30 min.展开更多
基金Supported by the National Natural Science Foundation of China(No.30771609)the National High-tech Research and Development Program of China(No.2007AA021004)
文摘Hepatitis E is an enterically transmitted viral disease caused by infection with hepatitis E virus（HEV）. HEV is a nonenveloped virus that bas been classified in the family of Caliciviridae. The virus appears to be a polya-denylated, positive-stranded RNA virus with three major open reading frames（ORFs）. The capsid protein of HEV is encoded by the open reading frame 2（ORF2）. We attempted to produce a truncated capsid protein, designed p293, in Pichia pastoris. The p293 gene encoding amino acids（aa） 382-674 of HEV ORF2 was designed based on the full length of HEV ORF2, cloned into the yeast vector pPIC9K, and expressed in P. pastoris strain GS 115. SDS-PAGE and Western blotting demonstrated that the recombinant protein p293 could well be expressed in P pastoris. Under optimized conditions （culture medium pH, 6.0-6.5; methanol concentration added daily, 3.0%; inoculum density, OD600=60; induction time point, 72-96 h）, the yield of soluble p293 was approximately 80 mg/L. We also observed p293 secretory expressed in P. pastoris to be 30 nm viral like particles by using electron microscopy. These results show that the p293 may has utility in the analysis of cell specific factors in the protein processing and assembly of HEV, and serve as a useful antigen for both diagnostic and vaccine purposes.
文摘Mammalian cells express two isoforms of Cu- and Zn-containing superoxide dismutases（SODs）, CuZn-SOD and extracellular SOD（EC-SOD）, involved in the defense system against reactive oxygen species（ROS）. The two SODs have structurally homologous centre domain with distinct N- and C-terminuses, resulting in the different characteristics of the structure and function of the two molecules. We generated a hybrid SOD molecule（namely hy- SOD） via replacing the N- and C-terminuses of hCuZnSOD with the counterparts of hEC-SOD. The hySOD was expressed in host Pichia pastoris and the purified protein was a dimer with a molecular weight of about 34000. A series of activity analyses indicates that the hySOD is similar to hEC-SOD in heat-stability, and has the activity of protecting the host cell against heat shock and oxidative stress. Our results show evidence for the study on the compound activity of multiple SOD molecules, and may be important for understanding the relationship between structure and function of hEC-SOD and hCuZnSOD.
基金This research was supported by International Foundation for Science(Grant No.B/3873-1)the National High Technology Research and Development Program of China(Grant Nos.2003AA241160 and 2005AA246010)International S&T Cooperation Program of China(Grant No.20050048).
文摘β-Mannanase catalyzes endo-wise hydrolysis of the backbone of mannan and heteromannan,which are abun-dant in the cell wall structure of ungerminated leguminous seeds.The mature β-mannanase originated from Bacillus subtilis was expressed in Pichia pastoris,a methylotrophic yeast,using the leader peptide sequence of Saccharomyces cerevisiae α-factor.The cultivation of β-mannanase express-ing Pichia pastoris yields up to 1.8 g/L protein.In the super-natant the activity of the 40 kDa—total mannanase attained a level of 1102.0 IU/mL.The properties of the β-mannanase were characterized.Optimum pH and temperature for the recombinant enzyme were 5.5 and 50℃ respectively.The enzyme was stable at pH 5.0-10.0 and maintained over 30%original activity after incubating at 70℃ for 30 min.
