Expression, purification, and lipolytic activity of recombinant human serum albumin fusion proteins with one domain of human growth hormone inPichia pastoris

Improving heterologous expression of porcine follicle-stimulating hormone in Pichia pastoris by integrating molecular strategies and culture condition optimization

Porcine follicle-stimulating hormone (pFSH), comprising α and β subunits, is commonly used to induce superovulation in domestic animals in assisted reproduction technologies; however, the practical application of pFSH is inhibited by the limited efficiency of its production. Recombinant yeast-derived FSH offers a practical alternative; however, the heterologous expression efficiency remains disappointingly low. To improve FSH production in Pichia pastoris, a series of molecular strategies, together with fermentation optimization, were tested in the present study. By comparing clones of the Mut^s phenotype strain, it was observed that the yield of soluble pFSH increased by approximately 96% in clones of the Mut⁺ phenotype strain. The protein levels of soluble pFSHβ, which confers biological specificity, increased by approximately 143 and 22% after two kinds of codon optimization strategies, respectively. Moreover, compared with the production of soluble pFSHβ and SUMO-pFSHβ, the production of soluble protein HSA-pFSHβ was significantly improved. Furthermore, the optimum pH and methanol concentration for expressing soluble HSA-pFSH in strain H3-3 were determined as 5.0-6.0 and 1.5-2% in shake-flask, and the yield of soluble HSA-pFSH could reach 40.8 mg/l after purification. In vitro bioactivity assays showed that recombinant HSA-pFSH could efficiently stimulate cAMP synthesis in HEK293 cells expressing porcine FSHR. In conclusion, our results demonstrated that the application of phenotypic selection of aox1 mutants, combined with codon optimization, the choice of fusion partners, and fermentation optimization, considerably increased the yield of pFSH in supernatant of P. pastoris and thus provided a valuable reference for the large-scale recombinant expression of pFSH.

A novel treatment for weight reduction by the recombinant "Pichia pastoris" yeast expressing the hybrid protein of "irisin-furin-transferrin"

Obesity is a major health problem across the world, but there are few ways to effectively treat or manage it in the long term. Researchers are searching for more convenient, cost-effective and noninvasive therapies for overweight and obese people. Recent studies have illustrated that the microbiome of the body's different organs can be used as a vehicle for in-situ gene therapy. We suggest that the recombinant form of "Pichia pastoris" yeast expressing the hybrid protein of "irisin-furin-transferrin" under the control of the enolase 1 promoter is a new nutraceutical strategy to absorb fewer calories from intestinal nutrients, and induce a higher metabolic rate to expend more calories, similar to that from engaging in physical activity. By comparison, this method can be a long-term, noninvasive treatment and can be used for obese patients who have movement limitations.

Engineering of a Pichia pastoris expression system for high-level secretion of HSA/GH fusion protein

Human serum albumin (HSA) and human growth hormone (hGH) fusion protein [HSA/GH] is a promising long-acting form of GH to treat GH deficiency. This study attempted to engineer a P. pastoris strain for high-level production of HSA/GH to be used in basic research and clinical application. Strains contained two, three, and seven copies of HSA/GH gene were screened by selecting against Zeocin resistance. The results revealed that introducing two to three copies of HSA/GH gene was sufficient to give a significant increase in secretion level, compared with one copy of HSA/GH gene. No significant differences were observed between two to three copies and seven copies. Co-expression with either one copy of exogenous ERO1 or PDI in a strain carrying multicopies of HSA/GH gene led to varying degrees of increase in HSA/GH secretion. The effect of introducing multicopies of PDI was similar to that of one copy of PDI, but introducing excess copies of ERO1 reduced HSA/GH secretion. Simultaneous co-expression with PDI and ERO1 was less effect than either PDI co-expression or ERO1 co-expression. A strain showing higher secretion level was successfully applied to large-scale fermentation with the productivity of 3-4 g/l.