The available promoters in the Pichia pastoris expression platform are still limited. We selected and identified a novel strong constitutive promoter, P GCW14 , and tested its promoter activity using enhanced green fluorescent protein (EGFP) as a reporter. Potential promoter regions of P GCW14 were cloned upstream of the EGFP gene and promoter activity was analyzed by measuring fluorescence intensity. P GCW14 exhibited significantly stronger promoter activity than the classic strong constitutive promoters P TEF1 and P GAP under various carbon sources, suggesting that P GCW14 is a strong and constitutive promoter. Hence, P GCW14 can be used as a promoter for high-level expression of heterologous proteins.

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An intravenously injectable liquid formulation of the poorly water-soluble isosteviol sodium (ISVNa) that has a great clinical potential for cardiovascular diseases was developed using the co-solvent technology. The pH and composition of the co-solvent were optimized to obtain a stable liquid formulation (termed as STVNa) based on saline at pH 10.0 containing 25% (v/v) of ethanol and 20% (v/v) of propylene glycol. STVNa was physicochemically stable upon storage for more than 3 months under various conditions. In vitro studies showed that STVNa did not induce hemolytic effects up to 9.1% (v/v) after 3 h of incubation and it was cytocompatible up to 50 μg/mL in H2C9 cells. Furthermore, STVNa showed acceptable safety and pharmacokinetic parameters comparable with those of ISVNa in saline (dissolved at 60 °C) upon i.v. injection in Wistar rats. Overall, the results demonstrated that STVNa is a promising formulation of ISVNa for clinical translation.

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BackgroundExisting treatments are inadequate for patients at high risk of coronary heart disease caused by elevated levels of plasma low-density lipoprotein cholesterol (LDL-C). Bambuterol is a prodrug of β2-agonist commonly used for the treatment of asthma and chronic obstructive pulmonary disease (COPD) with the advantage of once daily dosing and favorable side effect profile. The potential lipid-lowering effects of bambuterol were unclear, possibly due to the racemic bambuterol (rac-bambuterol) that was used in previous studies.MethodsThe lipid-lowering effects of R-bambuterol were examined in a randomized phase I trial in 48 healthy Chinese volunteers aged 18–45 years. Participants were randomly assigned to five groups to receive a single dose (2.5 mg, 5 mg or 10 mg) or multiple doses (5 mg) of oral medications of R-bambuterol, or a single dose of rac-bambuterol (10 mg). Plasma lipid levels were measured at baseline, time to peak concentration (Tmax) and 24 h after the treatment.FindingsAdministration of a single-dose of R-bambuterol resulted in dose-dependent reductions in the levels of plasma LDL-C, high-density lipoprotein cholesterol (HDL-C), total cholesterol (TC), apolipoprotein B (ApoB) and apolipoprotein A1 (ApoA1) at Tmax. Levels of LDL-C exhibited the most reductions, which were statistically significant in all three single-dose R-bambuterol groups (all P values < 0.05). R-bambuterol was more potent in LDL-C lowering compared to rac-bambuterol at Tmax (P = 0.08). At 24 h after dosing, the significant lipid lowering effects of R-bambuterol sustained for LDL-C (P = 0.01), ApoB (P = 0.001) and ApoA1 (P = 0.03), but not for HDL-C. The ratio of ApoA1/ApoB was marginally increased (P = 0.06). In the multiple-dose group, LDL-C levels again were significantly reduced (all P values < 0.05), whereas the ratios of ApoA1/ApoB were marginally increased.InterpretationR-bambuterol can lower the plasma levels of LDL-C, and marginally raise the ratio of ApoA1/ApoB (indicator of HDL-C/LDL-C) with both a single dose and multiple doses. R-bambuterol was more potent in LDL-C lowering than rac-bambuterol.

Background: Glycosylphosphatidylinositol (GPI)-anchored glycoproteins have diverse intrinsic functions in yeasts, and they also have different uses in vitro. In this study, the functions of potential GPI proteins in Pichia pastoris were explored by gene knockout approaches. Results: Through an extensive knockout of GPI proteins in P. pastoris, a single-gene deletion library was constructed for 45 predicted GPI proteins. The knockout of proteins may lead to the activation of a cellular response named the 'compensatory mechanism', which is characterized by changes in the content and relationship between cell wall polysaccharides and surface proteins. Among the 45 deletion strains, five showed obvious methanol tolerance, four owned high content of cell wall polysaccharides, and four had a high surface hydrophobicity. Some advantages of these strains as production hosts were revealed. Furthermore, the deletion strains with high surface hydrophobicity were used as hosts to display Candida antarctica lipase B (CALB). The strain gcw22Δ/CALB-GCW61 showed excellent fermentation characteristics, including a faster growth rate and higher hydrolytic activity. Conclusions: This GPI deletion library has some potential applications for production strains and offers a valuable resource for studying the precise functions of GPI proteins, especially their putative functions.

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