Codon optimization and expression of irisin in Pichia pastoris GS115

Coupling thermotolerance and high production of recombinant protein by CYR1N1546K mutation via cAMP signaling cascades

In recombinant protein-producing yeast strains, cells experience high production-related stresses similar to high temperatures. It is possible to increase recombinant protein production by enhancing thermotolerance, but few studies have focused on this topic. Here we aim to identify cellular regulators that can simultaneously activate thermotolerance and high yield of recombinant protein. Through screening at 46 °C, a heat-resistant Kluyveromyces marxianus (K. marxianus) strain FDHY23 is isolated. It also exhibits enhanced recombinant protein productivity at both 30 °C and high temperatures. The CYR1N1546K mutation is identified as responsible for FDHY23's improved phenotype, characterized by weakened adenylate cyclase activity and reduced cAMP production. Introducing this mutation into the wild-type strain greatly enhances both thermotolerance and recombinant protein yields. RNA-seq analysis reveals that under high temperature and recombinant protein production conditions, CYR1 mutation-induced reduction in cAMP levels can stimulate cells to improve its energy supply system and optimize material synthesis, meanwhile enhance stress resistance, based on the altered cAMP signaling cascades. Our study provides CYR1 mutation as a novel target to overcome the bottleneck in achieving high production of recombinant proteins under high temperature conditions, and also offers a convenient approach for high-throughput screening of recombinant proteins with high yields.

Improvement of duplex-specific nuclease salt tolerance by fusing DNA-binding domain of DNase from an extremely halotolerant bacterium Thioalkalivibrio sp. K90mix

Salt tolerance is an important property of duplex-specific nuclease (DSN). DSN with high salt tolerance can be more widely used in genetic engineering, especially in the production of nucleic acid drugs. To improve the salt tolerance of DSN, we selected five DNA-binding domains from extremophilic organisms, which have been shown the ability to improve salt tolerance of DNA polymerases and nucleases. The experimental results demonstrated that the fusion protein TK-DSN produced by fusing a N-terminal DNA-binding domain, which comprised two HhH (helix-hairpin-helix) motifs domain from an extremely halotolerant bacterium Thioalkalivibrio sp. K90mix, has a significantly improved salt tolerance. TK-DSN can tolerate the concentration of NaCl up to 800 mM; in addition, the ability of digesting DNA was also enhanced during in vitro transcription and RNA purification. This strategy provides the method for the personalized customization of biological tool enzymes for different applications.

Novel CaLB-like Lipase Found Using ProspectBIO, a Software for Genome-Based Bioprospection

Enzymes have been highly demanded in diverse applications such as in the food, pharmaceutical, and industrial fuel sectors. Thus, in silico bioprospecting emerges as an efficient strategy for discovering new enzyme candidates. A new program called ProspectBIO was developed for this purpose as it can find non-annotated sequences by searching for homologs of a model enzyme directly in genomes. Here we describe the ProspectBIO software methodology and the experimental validation by prospecting for novel lipases by sequence homology to Candida antarctica lipase B (CaLB) and conserved motifs. As expected, we observed that the new bioprospecting software could find more sequences (1672) than a conventional similarity-based search in a protein database (733). Additionally, the absence of patent protection was introduced as a criterion resulting in the final selection of a putative lipase-encoding gene from Ustilago hordei (UhL). Expression of UhL in Pichia pastoris resulted in the production of an enzyme with activity towards a tributyrin substrate. The recombinant enzyme activity levels were 4-fold improved when lowering the temperature and increasing methanol concentrations during the induction phase in shake-flask cultures. Protein sequence alignment and structural modeling showed that the recombinant enzyme has high similarity and capability of adjustment to the structure of CaLB. However, amino acid substitutions identified in the active pocket entrance may be responsible for the differences in the substrate specificities of the two enzymes. Thus, the ProspectBIO software allowed the finding of a new promising lipase for biotechnological application without the need for laborious and expensive conventional bioprospecting experimental steps.

Evaluation of two Plasmodium vivax sexual stage antigens as transmission-blocking vaccine candidates

BACKGROUND

Plasmodium vivax transmission-blocking vaccines (TBVs) are receiving increasing attention. Based on excellent transmission-blocking activities of the PbPH (PBANKA_0417200) and PbSOP26 (PBANKA_1457700) antigens in Plasmodium berghei, their orthologs in P. vivax, PVX_098655 (PvPH) and PVX_101120 (PvSOP26), were selected for the evaluation of their potential as TBVs.

METHODS

Fragments of PvPH (amino acids 22-304) and PvSOP26 (amino acids 30-272) were expressed in the yeast expression system. The recombinant proteins were used to immunize mice to obtain antisera. The transmission-reducing activities of these antisera were evaluated using the direct membrane feeding assay (DMFA) using Anopheles dirus mosquitoes and P. vivax clinical isolates.

RESULTS

The recombinant proteins PvPH and PvSOP26 induced robust antibody responses in mice. The DMFA showed that the anti-PvSOP26 sera significantly reduced oocyst densities by 92.0 and 84.1% in two parasite isolates, respectively, whereas the anti-PvPH sera did not show evident transmission-reducing activity. The variation in the DMFA results was unlikely due to the genetic polymorphisms of the two genes since their respective sequences were identical in the clinical P. vivax isolates.

CONCLUSION

PvSOP26 could be a promising TBV candidate for P. vivax, which warrants further evaluation.

Strategies and challenges with the microbial conversion of methanol to high-value chemicals

As alternatives to traditional fermentation substrates, methanol (CH₃ OH), carbon dioxide (CO₂ ) and methane (CH₄ ) represent promising one-carbon (C1) sources that are readily available at low-cost and share similar metabolic pathway. Of these C1 compounds, methanol is used as a carbon and energy source by native methylotrophs, and can be obtained from CO₂ and CH₄ by chemical catalysis. Therefore, constructing and rewiring methanol utilization pathways may enable the use of one-carbon sources for microbial fermentations. Recent bioengineering efforts have shown that both native and nonnative methylotrophic organisms can be engineered to convert methanol, together with other carbon sources, into biofuels and other commodity chemicals. However, many challenges remain and must be overcome before industrial-scale bioprocessing can be established using these engineered cell refineries. Here, we provide a comprehensive summary and comparison of methanol metabolic pathways from different methylotrophs, followed by a review of recent progress in engineering methanol metabolic pathways in vitro and in vivo to produce chemicals. We discuss the major challenges associated with establishing efficient methanol metabolic pathways in microbial cells, and propose improved designs for future engineering.

Novel Roles of Follistatin/Myostatin in Transforming Growth Factor-β Signaling and Adipose Browning: Potential for Therapeutic Intervention in Obesity Related Metabolic Disorders

Obesity is a global health problem and a major risk factor for several metabolic conditions including dyslipidemia, diabetes, insulin resistance and cardiovascular diseases. Obesity develops from chronic imbalance between energy intake and energy expenditure. Stimulation of cellular energy burning process has the potential to dissipate excess calories in the form of heat via the activation of uncoupling protein-1 (UCP1) in white and brown adipose tissues. Recent studies have shown that activation of transforming growth factor-β (TGF-β) signaling pathway significantly contributes to the development of obesity, and blockade or inhibition is reported to protect from obesity by promoting white adipose browning and increasing mitochondrial biogenesis. Identification of novel compounds that activate beige/brown adipose characteristics to burn surplus calories and reduce excess storage of fat are actively sought in the fight against obesity. In this review, we present recent developments in our understanding of key modulators of TGF-β signaling pathways including follistatin (FST) and myostatin (MST) in regulating adipose browning and brown adipose mass and activity. While MST is a key ligand for TGF-β family, FST can bind and regulate biological activity of several TGF-β superfamily members including activins, bone morphogenic proteins (BMP) and inhibins. Here, we review the literature supporting the critical roles for FST, MST and other proteins in modulating TGF-β signaling to influence beige and brown adipose characteristics. We further review the potential therapeutic utility of FST for the treatment of obesity and related metabolic disorders.

Expression of a novel dual-functional polypeptide and its pharmacological action research

AIMS

To develop a dual-functional medicine for hypoglycemic and anti-thrombus.

MAIN METHODS

The long-acting glucagon like peptide-1 (5×GLP-1) and nattokinase (NK) were cloned by SOE PCR and gained the GLP-1 and NK fusion polypeptide after transformed into E. coli. Use of mice models for the hypoglycemic and anti-thrombus activity of the fusion polypeptide. Balb/C mice were given the carrageenan by intraperitoneal injection to induce tail thrombus models. Type 2 diabetes mellitus mice model was used to research the hypoglycemic function of the fusion polypeptide.

KEY FINDINGS

Results showed that the fusion polypeptide could significantly prevent thrombus formation after oral administration. Continuous administration for 15 days, fasting blood glucose levels of the experimental group decreased to nearly normal levels.

SIGNIFICANCE

The present study investigated the expression, purification and functional activity of the rolGLP-1 and NK fusion polypeptide, which provided a foundation for further studying the detailed pharmaceutical mechanism and drug development.

Co-expressing GroEL-GroES, Ssa1-Sis1 and Bip-PDI chaperones for enhanced intracellular production and partial-wall breaking improved stability of porcine growth hormone

Porcine growth hormone (pGH) is a class of peptide hormones secreted from the pituitary gland, which can significantly improve growth and feed utilization of pigs. However, it is unstable and volatile in vitro. It needs to be encapsulated in liposomes when feeding livestock, whose high cost greatly limits its application in pig industry. Therefore we attempted to express pGH as intracellular soluble protein in Pichia pastoris and feed these yeasts with partial wall-breaking for swine, which could release directly pGH in intestine tract in case of being degraded in intestinal tract with low cost. In order to improve the intracellular soluble expression of pGH protein in Pichia pastoris and stability in vitro, we optimized the pGH gene, and screened molecular chaperones from E. coli and Pichia pastoris respectively for co-expressing with pGH. In addition, we had also explored conditions of mechanical crushing and fermentation. The results showed that the expression of intracellular soluble pGH protein was significantly increased after gene optimized and co-expressed with Ssa1-Sis1 chaperone from Pichia pastoris. Meanwhile, the optimal conditions of partial wall-breaking and fermentation of Pichia pastoris were confirmed, the data showed that the intracellular expression of the optimized pGH protein co-expressed with Ssa1-Sis1 could reach 340 mg/L with optimal conditions of partial wall-breaking and fermentation. Animal experiments verified that the optimized pGH protein co-expression with Ssa1-Sis1 had the best promoting effects on the growth of piglets. Our study demonstrated that Ssa1-Sis1 could enhance the intracellular soluble expression of pGH protein in Pichia pastoris and that partial wall-breaking of yeast could prevent pGH from degradation in vitro, release targetedly in the intestine and play its biological function effectively. Our study could provide a new idea to cut the cost effectively, establishing a theoretical basis for the clinic application of unstable substances in vitro.

Efficient Expression of Xylanase by Codon Optimization and Its Effects on the Growth Performance and Carcass Characteristics of Broiler

Simple Summary

The aim of this work was to combine xylanase expression and broiler production. The xylanase (XynB) gene from Trichoderma reesei was optimized to increase its expression level in Pichia pastoris. The maximum activity of xylanase (optiXynB) secreted by P. pastoris pPICZaA-optiXynB was 1299 U/mL after 96 h induction. The recombinase was highly specific towards birchwood xylan, beechwood xylan, and oat-spelt xylan. Dietary 1000 and 1500 IU/kg optiXynB significantly increased (p < 0.05) final weight and body weight gain; dietary 500, 1000, and 1500 IU/kg optiXynB significantly increased (p < 0.05) pre-evisceration weight, dressed percentage, and eviscerated weight compared with the control group. Results suggested that the optiXynB from P. pastoris pPICZaA-optiXynB has great application in broiler production.

Abstract

The aim of the present study was to improve the expression level of Trichoderma reesei xylanase (XynB) in Pichia pastoris through a codon optimization strategy and evaluate its effects on the growth performance and carcass characteristics of broiler. According to the codon bias of Pichia genome, the XynB gene from T. reesei was optimized and synthesized by whole gene assembly to improve its expression level in P. pastoris. Approximately 180 target mutations were successfully introduced into natural XynB. The maximum activity of xylanase (optiXynB) secreted by P. pastoris pPICZaA-optiXynB was 1299 U/mL after 96 h induction. Purified recombinant optiXynB had the molecular weight of 24 kDa. The optiXynB presented highest activity in pH 5.0 and 50 °C. The recombinase was highly specific towards birchwood xylan, beechwood xylan, and oat-spelt xylan. In the broiler experiment, a total of 200 Arbor Acre broilers (one day old) were randomly allocated into four groups fed with basal diets containing 0 (control group), 500, 1000, and 1500 IU/kg optiXynB. Dietary 1000 and 1500 IU/kg optiXynB significantly increased (p < 0.05) final weight and body weight gain; dietary 500, 1000, and 1500 IU/kg optiXynB significantly increased (p < 0.05) pre-evisceration weight, dressed percentage, and eviscerated weight compared with the control group. Inclusion of optiXynB in broiler diets linearly increased final weight, body weight gain, breast muscle weight and leg muscle weight, but linearly decreased feed conversion rate (p < 0.05). Furthermore, inclusion of optiXynB in broiler diets linearly and quadratically increased pre-evisceration weight, dressed percentage, and eviscerated weight (p < 0.05). The recombinant optiXynB from P. pastoris pPICZaA-optiXynB was beneficial in improving growth performance and carcass characteristics of broilers.

Optimized Expression and Characterization of a Novel Fully Human Bispecific Single-Chain Diabody Targeting Vascular Endothelial Growth Factor165 and Programmed Death-1 in Pichia pastoris and Evaluation of Antitumor Activity In Vivo

Bispecific antibodies, which can bind to two different epitopes on the same or different antigens simultaneously, have recently emerged as attractive candidates for study in various diseases. Our present study successfully constructs and expresses a fully human, bispecific, single-chain diabody (BsDb) that can bind to vascular endothelial growth factor 165 (VEGF165) and programmed death-1 (PD-1) in Pichia pastoris. Under the optimal expression conditions (methanol concentration, 1%; pH, 4.0; inoculum density, OD600 = 4, and the induction time, 96 h), the maximum production level of this BsDb is achieved at approximately 20 mg/L. The recombinant BsDb is purified in one step using nickel-nitrilotriacetic acid (Ni-NTA) column chromatography with a purity of more than 95%. Indirect enzyme-linked immune sorbent assay (ELISA) and sandwich ELISA analyses show that purified BsDb can bind specifically to VEGF165 and PD-1 simultaneously with affinities of 124.78 nM and 25.07 nM, respectively. Additionally, the BsDb not only effectively inhibits VEGF165-stimulated proliferation, migration, and tube formation in primary human umbilical vein endothelial cells (HUVECs), but also significantly improves proliferation and INF-γ production of activated T cells by blocking PD-1/PD-L1 co-stimulation. Furthermore, the BsDb displays potent antitumor activity in mice bearing HT29 xenograft tumors by inhibiting tumor angiogenesis and activating immune responses in the tumor microenvironment. Based on these results, we have prepared a potential bispecific antibody drug that can co-target both VEGF165 and PD-1 for the first time. This work provides a stable foundation for the development of new strategies by the combination of an angiogenesis inhibition and immune checkpoint blockade for cancer therapy.

Engineering strategies for enhanced production of protein and bio-products in Pichia pastoris: A review

Pichia pastoris has been recognized as one of the most industrially important hosts for heterologous protein production. Despite its high protein productivity, the optimization of P. pastoris cultivation is still imperative due to strain- and product-specific challenges such as promoter strength, methanol utilization type and oxygen demand. To address the issues, strategies involving genetic and process engineering have been employed. Optimization of codon usage and gene dosage, as well as engineering of promoters, protein secretion pathways and methanol metabolic pathways have proved beneficial to innate protein expression levels. Large-scale production of proteins via high cell density fermentation additionally relies on the optimization of process parameters including methanol feed rate, induction temperature and specific growth rate. Recent progress related to the enhanced production of proteins in P. pastoris via various genetic engineering and cultivation strategies are reviewed. Insight into the regulation of the P. pastoris alcohol oxidase 1 (AOX1) promoter and the development of methanol-free systems are highlighted. Novel cultivation strategies such as mixed substrate feeding are discussed. Recent advances regarding substrate and product monitoring techniques are also summarized. Application of P. pastoris to the production of biodiesel and other value-added products via metabolic engineering are also reviewed. P. pastoris is becoming an indispensable platform through the use of these combined engineering strategies.

High-level secretion and characterization of cyclodextrin glycosyltransferase in recombinant Komagataella phaffii

Cyclodextrin glycosyltransferase (CGTase) catalyzes the conversion of starch into cyclodextrin (CD), which is widely applied in food, pharmaceutical, cosmetic, and agricultural industries. For efficient production of CD, high yield of CGTase with good characteristics is necessary. In this study, the cgt gene from Bacillus pseudalcaliphilus was expressed in Komagataella phaffii after codon optimization and expression vector selection. The β-CGTase activity in the transformant reached 3885.1UmL^-1, which is the highest value reported so far, at 28°C, 6% inoculum ratio, and 1.5% methanol addition following 24h of incubation. The recombinant CGTase showed high specific activity at 80°C without any γ-CGTase activity, and had good stability in a wide pH and temperature range. These results demonstrate that the recombinant CGTase could have potential industrial applications.

Recombinant exochitinase of the thermophilic mould Myceliopthora thermophila BJA: Characteristics and utility in generating N-acetyl glucosamine and in biocontrol of phytopathogenic fungi

Chitinase from the thermophilic mould Myceliopthora thermophila BJA (MtChit) is an acid tolerant, thermostable and organic solvent stable biocatalyst which does not require any metal ions for its activity. To produce high enzyme titres, reduce fermentation time and overcome the need for induction, this enzyme has been heterologously expressed under GAP promoter in the GRAS yeast, Pichia pastoris. The production medium supplemented with the permeabilizing agent Tween-20 supported two-fold higher rMtChit production (5.5 × 10³ U L^-1 ). The consensus sequences S(132)xG(133)G(134) and D(168)xxD(171)xD(173)xE(175) in the enzyme have been found to represent the substrate binding and catalytic sites, respectively. The rMtChit, purified to homogeneity by a two-step purification strategy, is a monomeric glycoprotein of ∼48 kDa, which is optimally active at 55°C and pH 5.0. The enzyme is thermostable with t_1/2 values of 113 and 48 min at 65 and 75°C, respectively. Kinetic parameters K_m , V_max , k_cat , and k_cat /K_m of the enzyme are 4.655 mg mL^-1 , 34.246 nmol mg^-1  s^-1 , 3.425 × 10⁶ min^-1 , and 1.36 × 10^-6 mg mL^-1  min^-1 , respectively. rMtChit is an unique exochitinase, since its action on chitin liberates N-acetylglucosamine NAG. The enzyme inhibits the growth of phytopathogenic fungi like Fusarium oxysporum and Curvularia lunata, therefore, this finds application as biofungicide at high temperatures during summer in tropics. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:70-80, 2017.

Anti-diabetic activity of recombinant irisin in STZ-induced insulin-deficient diabetic mice

In order to investigate the hypoglycemic effects and potential mechanism of recombinant irisin on diabetes, STZ-induced diabetic mice were established and treated with irisin. The results showed that daily water and food intake, and blood glucose significantly decreased after various concentrations of recombinant irisin treatment by intraperitoneal injection, of which 1.0 mg/kg was the optimal dose for lowering blood glucose. However, the body weight exhibited no significant difference during the treatment within groups, although the 0.9% NaCl treated group showed a trend of decreased body weight and the irisin treated groups showed a tendency of increasing weight. The oral glucose tolerance was improved, and serum insulin and circulating irisin content were significantly elevated in diabetic mice after 1.0 mg/kg irisin-injection treatment, compared to diabetic mice treated with 0.9% NaCl. 1.0 mg/kg irisin-injection also significantly increased the expression of energy and metabolism-related genes. In addition, oral administration of irisin lowered the blood glucose in diabetic mice. Our data suggested that irisin could lower blood glucose in insulin-deficient diabetic mice, to some extent, through irisin-mediated induction of energy and metabolic genes expression. These observations laid a foundation for the development of irisin-based therapy.