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A native phosphoglycolate salvage pathway of the synthetic autotrophic yeast Komagataella phaffii.

ABSTRACT: Synthetic autotrophs can serve as chassis strains for bioproduction from CO₂ as a feedstock to take measures against the climate crisis. Integration of the Calvin-Benson-Bassham (CBB) cycle into the methylotrophic yeast Komagataella phaffii (Pichia pastoris) enabled it to use CO₂ as the sole carbon source. The key enzyme in this cycle is ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) catalyzing the carboxylation step. However, this enzyme is error prone to perform an oxygenation reaction leading to the production of toxic 2-phosphoglycolate. Native autotrophs have evolved different recycling pathways for 2-phosphoglycolate. However, for synthetic autotrophs, no information is available for the existence of such pathways. Deletion of CYB2 in the autotrophic K. phaffii strain led to the accumulation of glycolate, an intermediate in phosphoglycolate salvage pathways, suggesting that such a pathway is enabled by native K. phaffii enzymes. ¹³C tracer analysis with labeled glycolate indicated that the yeast pathway recycling phosphoglycolate is similar to the plant salvage pathway. This orthogonal yeast pathway may serve as a sensor for RuBisCO oxygenation, and as an engineering target to boost autotrophic growth rates in K. phaffii.

SUBMITTER: Baumschabl M

PROVIDER: S-EPMC10791038 | biostudies-literature | 2024

REPOSITORIES: biostudies-literature

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A native phosphoglycolate salvage pathway of the synthetic autotrophic yeast Komagataella phaffii.

Baumschabl Michael M Mitic Bernd M BM Troyer Christina C Hann Stephan S Ata Özge Ö Mattanovich Diethard D

microLife 20231211

Synthetic autotrophs can serve as chassis strains for bioproduction from CO2 as a feedstock to take measures against the climate crisis. Integration of the Calvin-Benson-Bassham (CBB) cycle into the methylotrophic yeast Komagataella phaffii (Pichia pastoris) enabled it to use CO2 as the sole carbon source. The key enzyme in this cycle is ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) catalyzing the carboxylation step. However, this enzyme is error p ...[more]

PMID: 38234447

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Project description:The yeast Komagataella phaffii has become a popular host strain among biotechnology start-up companies for producing recombinant proteins for food and adult nutrition applications. Komagataella phaffii is a host of choice due to its long history of safe use, open access to protocols and strains, a secretome free of host proteins and proteases, and contract manufacturing organizations with deep knowledge in bioprocess scale-up. However, a recent publication highlighted the abundance of an unknown polysaccharide that accumulates in the supernatant during fermentation. This poses a significant challenge in using K. phaffii as a production host. This polysaccharide leads to difficulties in achieving high purity products and requires specialized and costly downstream processing steps for removal. In this study, we describe the use of the common K. phaffii host strain YB-4290 for production of the bioactive milk protein lactoferrin. Upon purification of lactoferrin using membrane-based separation methods, significant amounts of carbohydrate were copurified with the protein. It was determined that the carbohydrate is mostly composed of mannose residues with minor amounts of glucose and glucosamine. The polysaccharide fraction has an average molecular weight of 50 kDa and consists mainly of mannan, galactomannan, and amylose. In addition, a large fraction of the carbohydrate has an unknown structure likely composed of oligosaccharides. Additional strains were tested in fermentation to further understand the source of the carbohydrates. The commonly used industrial hosts, BG10 and YB-4290, produce a basal level of exopolysaccharide; YB-4290 producing slightly more than BG10. Overexpression of recombinant protein stimulates exopolysaccharide production well above levels produced by the host strains alone. Overall, this study aims to provide a foundation for developing methods to improve the economics of recombinant protein production using K. phaffii as a production host.One-sentence summaryOverexpression of recombinant protein stimulates the hyperproduction of high-molecular-weight, mannose-based, exopolysaccharides by the industrial yeast Komagataella phaffii.

Project description:BackgroundMethanol is increasingly gaining attraction as renewable carbon source to produce specialty and commodity chemicals, as it can be generated from renewable sources such as carbon dioxide (CO2). In this context, native methylotrophs such as the yeast Komagataella phaffii (syn Pichia pastoris) are potentially attractive cell factories to produce a wide range of products from this highly reduced substrate. However, studies addressing the potential of this yeast to produce bulk chemicals from methanol are still scarce. 3-Hydroxypropionic acid (3-HP) is a platform chemical which can be converted into acrylic acid and other commodity chemicals and biopolymers. 3-HP can be naturally produced by several bacteria through different metabolic pathways.ResultsIn this study, production of 3-HP via the synthetic β-alanine pathway has been established in K. phaffii for the first time by expressing three heterologous genes, namely panD from Tribolium castaneum, yhxA from Bacillus cereus, and ydfG from Escherichia coli K-12. The expression of these key enzymes allowed a production of 1.0 g l-1 of 3-HP in small-scale cultivations using methanol as substrate. The addition of a second copy of the panD gene and selection of a weak promoter to drive expression of the ydfG gene in the PpCβ21 strain resulted in an additional increase in the final 3-HP titer (1.2 g l-1). The 3-HP-producing strains were further tested in fed-batch cultures. The best strain (PpCβ21) achieved a final 3-HP concentration of 21.4 g l-1 after 39 h of methanol feeding, a product yield of 0.15 g g-1, and a volumetric productivity of 0.48 g l-1 h-1. Further engineering of this strain aiming at increasing NADPH availability led to a 16% increase in the methanol consumption rate and 10% higher specific productivity compared to the reference strain PpCβ21.ConclusionsOur results show the potential of K. phaffii as platform cell factory to produce organic acids such as 3-HP from renewable one-carbon feedstocks, achieving the highest volumetric productivities reported so far for a 3-HP production process through the β-alanine pathway.

Project description:BackgroundKomagataella phaffii (Pichia pastoris) is a methylotrophic commercially important non-conventional species of yeast that grows in a fermentor to exceptionally high densities on simple media and secretes recombinant proteins efficiently. Genetic engineering strategies are being explored in this organism to facilitate cost-effective biomanufacturing. Small, stable artificial chromosomes in K. phaffii could offer unique advantages by accommodating multiple integrations of extraneous genes and their promoters without accumulating perturbations of native chromosomes or exhausting the availability of selection markers.ResultsHere, we describe a linear "nano"chromosome (of 15-25 kb) that, according to whole-genome sequencing, persists in K. phaffii over many generations with a copy number per cell of one, provided non-homologous end joining is compromised (by KU70-knockout). The nanochromosome includes a copy of the centromere from K. phaffii chromosome 3, a K. phaffii-derived autonomously replicating sequence on either side of the centromere, and a pair of K. phaffii-like telomeres. It contains, within its q arm, a landing zone in which genes of interest alternate with long (approx. 1-kb) non-coding DNA chosen to facilitate homologous recombination and serve as spacers. The landing zone can be extended along the nanochromosome, in an inch-worming mode of sequential gene integrations, accompanied by recycling of just two antibiotic-resistance markers. The nanochromosome was used to express PDI, a gene encoding protein disulfide isomerase. Co-expression with PDI allowed the production, from a genomically integrated gene, of secreted murine complement factor H, a plasma protein containing 40 disulfide bonds. As further proof-of-principle, we co-expressed, from a nanochromosome, both PDI and a gene for GFP-tagged human complement factor H under the control of PAOX1 and demonstrated that the secreted protein was active as a regulator of the complement system.ConclusionsWe have added K. phaffii to the list of organisms that can produce human proteins from genes carried on a stable, linear, artificial chromosome. We envisage using nanochromosomes as repositories for numerous extraneous genes, allowing intensive engineering of K. phaffii without compromising its genome or weakening the resulting strain.

Dataset Information

A native phosphoglycolate salvage pathway of the synthetic autotrophic yeast Komagataella phaffii.

Publications

A native phosphoglycolate salvage pathway of the synthetic autotrophic yeast <i>Komagataella phaffii</i>.

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