Open Pichia
Our iGEM team selected the OPENPichia pep4 yps1 strain as the foundation for our protein production system after careful evaluation of available chassis organisms and their suitability for synthetic biology applications. This engineered strain of Komagataella phaffii (formerly Pichia pastoris) represents an optimal balance of technical performance, accessibility, and scalability that aligns with both our project goals and iGEM's principles of open science.
General Information
The defining characteristic that drove our selection is the strain's significantly enhanced protein stability profile. OPENPichia pep4 yps1 contains large deletions in two major secreted proteases—pep4p (Δaa80-aa307) and yps1p (Δaa80-aa513)—responsible for degrading substantial numbers of recombinantly produced proteins. By eliminating these proteolytic activities, the strain dramatically reduces protein degradation, resulting in higher yields and better integrity of secreted recombinant proteins. Additionally, the strain incorporates a HOC1 truncation mutation that significantly improves transformation efficiency compared to wild-type strains, making it highly amenable to genetic engineering.
| Gene Target | Function | Impact |
|---|---|---|
| pep4 (Δaa80-aa307) | Major secreted protease | Reduces protein degradation |
| yps1 (Δaa80-aa513) | Major secreted protease | Reduces protein degradation |
| HOC1 truncation mutation | α-1,6-mannosyltransferase | Improves transformation efficiency |
Strain Characteristics
The absence of killer plasmids in OPENPichia pep4 yps1 eliminates potential biosynthetic burden and toxicity issues that could affect culture viability and consistency. The improved transformation efficiency, achieved through the HOC1 truncation, increases transformation rates by 1.5–3 fold compared to wild-type strains. The dramatically reduced protease activity minimizes degradation of recombinant proteins, leading to enhanced stability and recovery. The strain construction uses split-marker technology ensuring all modifications are free from intellectual property restrictions.
| Characteristic | Status / Description |
|---|---|
| Killer Plasmids | Free (absent) |
| Transformation Efficiency | Enhanced (due to HOC1 truncation) |
| Protease Activity | Significantly reduced |
| Protein Stability | Improved for recombinant proteins |
| Construction Method | Marker-free split marker technology |
Applications and Benefits
In biopharmaceutical applications, OPENPichia pep4 yps1 offers superior protein integrity due to reduced proteolytic degradation. For industrial enzyme production, the strain provides consistent yields and reduced batch-to-batch variation. Research applications benefit from improved protein recovery rates, while commercial use gains from higher yields and the absence of licensing restrictions.
| Application Area | Benefit |
|---|---|
| Biopharmaceuticals | Greater protein integrity and yield |
| Industrial Enzymes | Reduced product degradation |
| Research | Better protein recovery |
| Commercial Production | Cost-effective due to higher yields |
Open Science and Accessibility
Equally important to our selection was OPENPichia’s commitment to open science. Unlike many industrial strains encumbered with restrictive licensing, OPENPichia strains are available for a nominal one-time fee and permit unrestricted research, distribution, and manufacturing. This open model eliminates major barriers that hinder translation of laboratory innovations into real-world impact.
The strain’s development using free-to-operate split-marker technology ensures derivative strains and applications can be freely shared within the scientific community — a principle central to iGEM’s spirit of collaboration and accessibility.
References
- Claes, K., Van Herpe, D., Vanluchene, R., Roels, C., Van Moer, B., Wyseure, E., ... & Callewaert, N. (2024). OPENPichia: licence-free Komagataella phaffii chassis strains and toolkit for protein expression. Nature Microbiology, 9(3), 864–876.
- OPENPichia Strains | OPENPichia