Part:BBa_K5059000
Alpha-Amyrin Synthase (AAS)
This sequence resembles the MdOSC1 variant of the alpha-amyrin synthase from Malus domestica. Alpha-amyrin synthase (AAS) converts 2,3-oxidosqualene to alpha-amyrin, the precursor for ursolic acid in the mevalonate pathway [1]. Since S. cerevisiae doesn't contain AAS, we integrated this sequence into its genome to successfully produce ursolic acid. We codon-optimized the sequence using Benchling to be compatible with iGEM Assembly Standards. Since the sequence is over 2000 base pairs, we split the sequence into two parts, Thing 1 and Thing 2, so that we could order the parts through IDT. We designed an overlapping EcoRI region so the sequences would be digested and then ligated together using T4 ligase. We also attached a 6xHis tag at the end of the sequence to enable Ni-NTA affinity chromatography for convenient enzyme isolation.
After designing BBa_K5059000, we implemented it in BBa_K5059001, a composite part, to increase the expression of BBa_K5059000.
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]
Usage and Biology
Ursolic acid has gained traction recently as a potential therapeutic agent. Preliminary studies have been done on ursolic acid, determining its therapeutic potential for cancer, liver disease, and obesity, among other health benefits [2]. There is particular interest in ursolic acid's properties in fighting cancer, as it is an antioxidant and anti-inflammatory agent. Clinical trials are currently underway to test its use in cancer-treating drugs. However, the current method for ursolic acid extraction from fruits, such as apples and loquats, is inefficient, environmentally taxing, and expensive. By engineering S. cerevisiae to produce ursolic acid, the traditional method for its extraction can be bypassed by utilizing the pathway shown below.
Within this pathway, AAS is the first enzyme required to catalyze ursolic acid production. Specifically, it catalyzes the conversion of 2,3-oxidosqualene to alpha-amyrin, which is the direct precursor for ursolic acid through the action of Cytochrome P450, which is activated via Cytochrome P450 reductase donating an electron from NADPH to it.
Functionality
Catalytic Efficiency
| Substrate | Product | Km (µM) | kcat (min^-1) | kcat/Km (min^-1/µM) |
|---|---|---|---|---|
| 1. 2,3-oxidosqualene | alpha-amyrin | 50.07 | 43.4 | 0.87 |
| 2. alpha-amyrin | Ursolic Acid | 24.5 | 35 | 1.43 |
References
[1] Jia, N., Li, J., Zang, G., Yu, Y., Jin, X., He, Y., Feng, M., Na, X., Wang, Y., & Li, C. (2024). Engineering Saccharomyces cerevisiae for high-efficient production of ursolic acid via cofactor engineering and acetyl-CoA optimization. Biochemical Engineering Journal, 203, 109189. https://doi.org/10.1016/j.bej.2023.109189
[2] Alam, M., Ali, S., Ahmed, S., Elasbali, A. M., Adnan, M., Islam, A., Hassan, Md. I., & Yadav, D. K. (2021). Therapeutic Potential of Ursolic Acid in Cancer and Diabetic Neuropathy Diseases. International Journal of Molecular Sciences, 22(22), 12162. https://doi.org/10.3390/ijms222212162
[3] Yu, Y., Chang, P., Yu, H., Ren, H., Hong, D., Li, Z., Wang, Y., Song, H., Huo, Y., & Li, C. (2018). Productive Amyrin Synthases for Efficient α-Amyrin Synthesis in Engineered Saccharomyces cerevisiae. ACS Synthetic Biology, 7(10), 2391–2402. https://doi.org/10.1021/acssynbio.8b00176
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