High-level extracellular expression of inulin fructotransferase in Pichia pastoris for DFA III production

A self-inducible heterologous protein expression system in Komagataella phaffii (Pichia pastoris)

Komagataella phaffii (previously described as Pichia pastoris) is a yeast that produces high-level heterologous proteins with a wide range of applications in medicine and industry. The methanol-induced alcohol oxidase I promoter (PAOX1) is frequently used for protein expression in this yeast. However, limitations on the use of methanol have been observed in large-scale production, including its flammability, toxicity, and need for special handling. Here, we propose to develop a system using recombinant cells constitutively expressing pectinmethyl esterase for expression of two reporter proteins, GFP and azurin, under the control of PAOX1 using pectin in production medium. So, this system is coherent with yeast culture medium containing pectin and heterologous gene inserted downstream of PAOX1 can be successfully expressed without the addition of methanol. Therefore, this novel Self-inducibLe heterologous protein EXpression (SILEX) system, which does not require the addition of methanol, can be used for the production of any protein. It can also be adapted for large-scale production.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-04039-x.

Difructose anhydride III: a 50-year perspective on its production and physiological functions

Production and applications of difructose anhydride III (DFA-III) have attracted considerable attention because of its versatile physiological functions. Recently, large-scale production of DFA-III has been continuously explored, which opens a horizon for applications in the food and pharmaceutical industries. This review updates recent advances involving DFA-III, including: biosynthetic strategies, purification, and large-scale production of DFA-III; physiological functions of DFA-III and related mechanisms; DFA-III safety evaluations; present applications in food systems, existing problems, and further research prospects. Currently, enzymatic synthesis of DFA-III has been conducted both industrially and in academic research. Two biosynthetic strategies for DFA-III production are summarized: single- and double enzyme-mediated. DFA-III purification is achieved via yeast fermentation. Enzyme membrane bioreactors have been applied to meet the large-scale production demands for DFA-III. In addition, the primary physiological functions of DFA-III and their underlying mechanisms have been proposed. However, current applications of DFA-III are limited. Further research regarding DFA-III should focus on commercial production and purification, comprehensive study of physiological properties, extensive investigation of large-scale human experiments, and expansion of industrial applications. It is worthy to dig deep into potential application and commercial value of DFA-III.

Heterologous expression of azurin from Pseudomonas aeruginosa in the yeast Pichia pastoris

Azurin, which is a bacterial secondary metabolite has been attracted as a potential anticancer agent in recent years because induced death of cancer cells and inhibited their growth. In this study, the production of azurin under the control of the alcohol oxidase promoter which is frequently used in the Pichia pastoris expression system was performed. The azurin gene amplified from Pseudomonas aeruginosa genomic DNA and inserted into the pPICZαA was cloned in Escherichia coli cells. Then, a linearized recombinant vector was transferred to the P. pastoris X-33 cells. Antibiotic resistance test and colony PCR were performed for the selection of multicopy transformants. Protein expression capacities of selected transformants were compared at the end of 48 h incubation. Both extracellular and intracellular protein expressions were observed in all of them by Western blot analysis. The relative expression levels of both intracellular and extracellular protein that belongs to the first clone were higher than the others. On the other hand, it was seen that the 4th clone had the highest protein secretion ability. The molecular mass of the extracellular azurin protein which is produced by recombinant clones was found to be about 20 kDa. This is the first report on azurin expression in P. pastoris.

Enhanced expression of human prostaglandin H synthase-2 in the yeast Pichia pastoris and removal of the C-terminal tag with bovine carboxypeptidase A

Vertebrate prostaglandin H synthases (PGHSs) are membrane-bound disulphide-containing hemoglycoproteins. Therefore, eukaryotic expression systems are required for the production of recombinant PGHSs. Recently we announced the expression of human PGHS-2 (hPGHS-2) in the yeast Pichia pastoris. Here we report improved production of hPGHS-2 in P. pastoris and a convenient method for the purification and de-tagging of the protein. An affinity tag comprised of a proline, a glycine and eight histidines was introduced into the C-terminal end of hPGHS-2. The tagged hPGHS-2 was expressed intracellularly in P. pastoris under the control of a constitutive or methanol-inducible promoter. Compared to constitutive expression, methanol-induced expression yielded approximately four times more protein. The analysis of high and low gene copy number recombinants revealed a positive correlation between the gene copy number and the expression level of hPGHS-2. The recombinant hPGHS-2 was purified using immobilised metal ion affinity chromatography. A novel elution method, treatment of the affinity resin with bovine carboxypeptidase A, was employed. The yield of pure de-tagged hPGHS-2 from 1l of yeast culture was approximately 3mg. The protein purification process with simultaneous removal of the C-terminal polyhistidine tag could be easily applied for the affinity purification of other proteins.

Secreted expression of truncated capsid protein from porcine circovirus type 2 in Pichia pastoris

OBJECTIVE

To achieve secreted expression of the truncated capsid protein from porcine circovirus type 2 (PCV2) in Pichia pastoris.

RESULTS

A truncated cap gene (tcap) with a deleted N-terminal nuclear localization signal was optimized and synthesized. Effective secreted expression was achieved in P. pastoris GS115. The high-productive recombinant strain for tCap was grown in a 5 l bioreactor and the productivity of tCap in supernatant reached 250 μg/ml. Furthermore, serum antibody test demonstrated that adjuvant-assisting tCap induced a significant increase of specific PCV2-Cap antibody over time in mice and a similar antibody level in pigs compared with a commercial Cap-based subunit vaccine.

CONCLUSION

This work establishes a secreted expression strategy in P. pastoris for the production of PCV2 Cap with superior bioactivity, and this strategy might provide potential uses in developing Cap-based subunit vaccine in the future.