Metabolic Engineering of the Methylotrophic Yeast Pichia Pastoris (Komagataella phaffii) for the Production of Β-alanine From Methanol

β-Alanine (3-aminopropionic acid), is the only naturally occurring β-amino acid and an important precursor for the synthesis of a variety of nitrogen-containing chemicals. Fermentative production of β-alanine from renewable feedstocks such as glucose has attracted significant interest in recent years. Methanol has become an emerging and promising renewable feedstock for biomanufacturing as an alternative to glucose. In this work, we demonstrated the feasibility of β-alanine production from methanol using Pichia pastoris (Komagataella phaffii) as a methylotrophic cell factory. Aspartate decarboxylases (ADCs) from different sources were screened and expressed in P. pastoris, followed by the optimization of aspartate decarboxylation by increasing the ADC copy number and C4 precursor supply via the overexpression of aspartate dehydrogenase. The production potential of the best strain was further evaluated in a 1-liter fermenter, and a β-alanine titer of 5.6 g/L was obtained. To our best knowledge, this is the highest chemical production titer ever reached in P. pastoris using methanol as the substrate.

Production of a Human Histamine Receptor for NMR Spectroscopy in Aqueous Solutions

G protein-coupled receptors (GPCRs) bind a broad array of extracellular molecules and transmit intracellular signals that initiate physiological responses. The signal transduction functions of GPCRs are inherently related to their structural plasticity, which can be experimentally observed by spectroscopic techniques. Nuclear magnetic resonance (NMR) spectroscopy in particular is an especially advantageous method to study the dynamic behavior of GPCRs. The success of NMR studies critically relies on the production of functional GPCRs containing stable-isotope labeled probes, which remains a challenging endeavor for most human GPCRs. We report a protocol for the production of the human histamine H1 receptor (H1R) in the methylotrophic yeast Pichia pastoris for NMR experiments. Systematic evaluation of multiple expression parameters resulted in a ten-fold increase in the yield of expressed H1R over initial efforts in defined media. The expressed receptor could be purified to homogeneity and was found to respond to the addition of known H1R ligands. Two-dimensional transverse relaxation-optimized spectroscopy (TROSY) NMR spectra of stable-isotope labeled H1R show well-dispersed and resolved signals consistent with a properly folded protein, and 19F-NMR data register a response of the protein to differences in efficacies of bound ligands.

Molecular Cloning and Heterologous Expression of Manganese(II)-Oxidizing Enzyme from Acremonium strictum Strain KR21-2

Diverse ascomycete fungi oxidize manganese(II) [Mn(II)] and produce Mn(III, IV) oxides in terrestrial and freshwater environments. Although multicopper oxidase (MCO) is considered to be a key catalyst in mediating Mn(II) oxidation in ascomycetes, the responsible gene and its product have not been identified. In this study, a gene, named mco1, encoding Mn(II)-oxidizing MCO from Acremonium strictum strain KR21-2 was cloned and heterologously expressed in the methylotrophic yeast Pichia pastoris. Based on the phylogenetic relationship, similarity of putative copper-binding motifs, and homology modeling, the gene product Mco1 was assigned to a bilirubin oxidase. Mature Mco1 was predicted to be composed of 565 amino acids with a molecular mass of 64.0 kDa. The recombinant enzyme oxidized Mn(II) to yield spherical Mn oxides, several micrometers in diameter. Zinc(II) ions added to the reaction mixture were incorporated by the Mn oxides at a Zn/Mn molar ratio of 0.36. The results suggested that Mco1 facilitates the growth of the micrometer-sized Mn oxides and affects metal sequestration through Mn(II) oxidation. This is the first report on heterologous expression and identification of the Mn(II) oxidase enzyme in Mn(II)-oxidizing ascomycetes. The cell-free, homogenous catalytic system with recombinant Mco1 could be useful for understanding Mn biomineralization by ascomycetes and the sequestration of metal ions in the environment

Expression and Purification of Active Human Kinases Using Pichia pastoris as A General-Purpose Host

Background: The heterologous expression of human kinases in good purity and in a monomeric, soluble and active form can be challenging. Most of the reported successful attempts are carried out in insect cells as a host. The use of E. coli for expression is limited to a few kinases and usually is facilitated by large solubility tags that can limit biophysical studies and affect protein–protein interactions. In this report, we evaluate the methylotrophic yeast Pichia pastoris (P. pastoris) as a general-purpose host for expression of human kinases. Methods: Six diverse kinases were chosen due to their therapeutic importance in human cancers. Tested proteins include serine/threonine kinases cyclin-dependent kinases 4 and 6 (CDK4 and 6) and aurora kinase A (AurKA), receptor tyrosine kinase erbB-2 (HER2), and dual specificity kinase mitogen-activated protein kinase kinase 3 (MKK3b). Noting that positively charged kinases expressed with higher yield, we sought to improve expression of two challenging targets, CDK6 and HER2, by fusing the highly basic, N-terminal domain of the secreted tyrosine-protein kinase VLK. A standard expression procedure was developed for P. pastoris, followed by purification using affinity chromatography. Purity and activity of the proteins were confirmed and compared to published values. Results: Some kinases were purified with good yield and purity and with comparable activity to commercially available versions. Addition of the VLK domain improved expression and decreased aggregation of CDK6 and HER2. Conclusions: P. pastoris is a promising host for expression of soluble and active human kinases.

Improved Protocol for the Production of the Low-Expression Eukaryotic Membrane Protein Human Aquaporin 2 in Pichia pastoris for Solid-State NMR

Solid-state nuclear magnetic resonance (SSNMR) is a powerful biophysical technique for studies of membrane proteins; it requires the incorporation of isotopic labels into the sample. This is usually accomplished through over-expression of the protein of interest in a prokaryotic or eukaryotic host in minimal media, wherein all (or some) carbon and nitrogen sources are isotopically labeled. In order to obtain multi-dimensional NMR spectra with adequate signal-to-noise ratios suitable for in-depth analysis, one requires high yields of homogeneously structured protein. Some membrane proteins, such as human aquaporin 2 (hAQP2), exhibit poor expression, which can make producing a sample for SSNMR in an economic fashion extremely difficult, as growth in minimal media adds additional strain on expression hosts. We have developed an optimized growth protocol for eukaryotic membrane proteins in the methylotrophic yeast Pichia pastoris. Our new growth protocol uses the combination of sorbitol supplementation, higher cell density, and low temperature induction (LT-SEVIN), which increases the yield of full-length, isotopically labeled hAQP2 ten-fold. Combining mass spectrometry and SSNMR, we were able to determine the nature and the extent of post-translational modifications of the protein. The resultant protein can be functionally reconstituted into lipids and yields excellent resolution and spectral coverage when analyzed by two-dimensional SSNMR spectroscopy.

Expression and Purification of Active Human Kinases Using Pichia pastoris as A General-Purpose Host

The heterologous expression of human kinases in good purity and monomer, soluble and active form can become a challenging feat. Most of the reported successful attempts are carried out in insect cells as a host. The use of E. coli for expression is limited to a few kinases and usually is facilitated by large solubility tags that can limit biophysical studies and affect protein–protein interactions. In this report, we evaluate the methylotrophic yeast Pichia pastoris as a general-purpose host for expression of human kinases. Methods: Six diverse kinases were chosen due to their therapeutic importance in human cancers. Tested proteins include serine/threonine kinases cyclin-dependent kinases 4 and 6 (CDK4 and 6) and aurora kinase A (AurKA), receptor tyrosine kinase erbB-2 (HER2), and dual specificity kinase mitogen-activated protein kinase kinase 3 (MKK3b). Two challenging targets, CDK6 and HER2, were fused to the highly basic, N-terminal domain of the secreted tyrosine-protein kinase VLK. Standard expression procedure in Pichia pastoris used. Purification was done using affinity chromatography, purity and identity of the proteins were confirmed and compared. Results: Some of the tested kinases expressed with good yield and purity and comparable activity to commercially available versins. Addition of the VLK domain improved expression and decreased aggregation of two of the challenging CDK6 and HER2. This can be attributed to a correlation we observed between the protein pI and its expression level in P. pastoris, where basic proteins are more likely to be expressed and purified. Conclusions: This study introduces P. pastoris as a promising host for expression of soluble and active human kinases.

PENGARUH VARIASI KONSENTRASI METANOL DAN LAMA INDUKSI TERHADAP EKSPRESI PROINSULIN OLEH Pichia pastoris SECARA INTRASELULER

The Effects of Variation in Methanol Concentration and Induction Time on Intracellular Proinsulin Expression by Pichia pastoris ABSTRACTDiabetes is a metabolic disorder characterized by hyperglycemia. There were 215 million diabetic patients in 2014 and the number is expected to rise in 2040. Generally, insulin is used to treat diabetic patients. Insulin production by recombinant technology has been done, though still inefficient, by using E. coli and S. cerevisiae expression system. Another alternative expression system is methylotrophic yeast Pichia pastoris. In this research, proinsulin has been expressed by P. pastoris intracellularly. P. pastoris strains used in this research were X33, GS115, and KM71H. All recombinant strains were MutS. Best cultivation media was BMGY. Proinsulin expression was observed at 25°C. Pichia pastoris strain that expressed proinsulin best was GS115-PI. It was supported by PCR in which the strain GS115-PI gave 504 bp-sized bands. Based on proinsulin formation time, the final methanol concentration of 0.5% in 72 hours was found to be the best treatment.Keywords: BMGY, methanol, phenotype, Pichia pastoris, proinsulin ABSTRAKDiabetes melitus merupakan kelainan yang ditandai dengan hiperglikemia. Penderita diabetes pada tahun 2014 di dunia mencapai 215 juta dan diperkirakan akan meningkat pada tahun 2040. Umumnya penderita diabetes diberi pengobatan insulin sehingga menunjukkan akan ada peningkatan kebutuhan insulin. Produksi insulin dengan teknologi DNA rekombinan telah dilakukan dengan menggunakan sistem ekspresi E. coli dan S. cerevisiae namun masih belum efisien. Sistem alternatif lain adalah ragi metilotropik Pichia pastoris. Dalam penelitian ini dilakukan ekspresi proinsulin dari P. pastoris secara intraseluler. Galur P. pastoris yang digunakan dalam penelitian ini adalah X33, GS115, dan KM71H. Semua galur rekombinan adalah MutS. Media tumbuh terbaik adalah BMGY. Ekspresi proinsulin terlihat pada suhu 25°C. Hasil PCR menunjukkan bahwa galur GS115-PI yang dapat menghasilkan pita amplikon berukuran 504 bp. Hasil PCR ini dibuktikan oleh hasil seleksi galur yang menunjukkan bahwa galur GS115-PI dapat mengekspresi proinsulin dibandingkan galur lainnya. Berdasarkan kecepatan pembentukan pita protein proinsulin, variasi konsentrasi akhir metanol 0,5% dengan lama induksi 72 jam merupakan perlakuan terbaik.Kata Kunci: BMGY, fenotipe, metanol, Pichia pastoris, proinsulin