Part
Basic Part
This year, our team uses a new kind of cell-surface display system-Ice Nucleation Protein (INP) as a new kind of basic part
(BBa_K2552003).
The full-length INPs are comprised of three distinct structural domains distinguished as the N-terminal domain (15%), the C-terminal domain (4%) and the central repeating domain (81%). In our team, we use the N-terminal domain of full-length INP as an anchoring motif to display T antigen.
Another kind of wildly used cell-surface display system is the OmpA system. Considering more and more teams are focusing on cancer targeting, we add a 15-amino acids oligo peptide to the C-terminal of OmpA to give it the ability to target cancer. The oligo peptide has the ability to bind to Thomsen–Friedenreich antigen (T antigen) that exist on some kinds of cancer cells (like colorectal cancer) by a mechanism similar to antigen-antibody binding reaction
(BBa_K2552005).
We also add a basic part
(BBa_K2552007)
that uses the Pyear promoter to regulate the expression of the azurin protein. With the lysis of our strain, the azurin protein is released to kill the CRC cells at the lesion position.
Composite Part
In our project this year, we add an important composite part which contains OmpA (a cell-surface display system of E.coli), oligo peptide T-1 and a Pyear promoter with the azurin protein
(BBa_K2552008).
E.coli contains plasmid with this composite part can gain the ability to catch colorectal cancer (CRC) cells under the control of Pyear promoter.
Because of the high concentration of nitric oxide around colorectal cancer in our gut, Pyear promoter can limit the expression of azurin after sensing nitric oxide in the vicinity of colorectal cancer. The whole circuit is constructed into the plasmid pCDF-Duet1 dual-expression vector for our experiments. As the result showed in our result page, Pyear is sensitive to nitric oxide and oligo peptide T-1 is able to target colorectal cancer cells efficiently. This composite part is well constructed to target and bind to colorectal cancer cells with controllable expression of subsequent drugs by Pyear.
Fig 1. The composite part of Ompa-Oligo peptide T-1-PyeaR-azurin.
Part Collection
In this year’s project, one of our most important parts is the adhesion between our engineered E.coli and the cancerous cells. In order to equip our bacteria with this function, we developed several biobricks for attachment through antigen-peptide binding. The main information and corresponding links are listed below.
Table 1. Part Collections
| Part | Registry Name | Type |
|---|---|---|
| Oligo Peptide T-1 | BBa_K2552000 | Protein_Domain |
| Oligo Peptide T-2 | BBa_K2552001 | Protein_Domain |
| Oligo Peptide T-3 | BBa_K2552002 | Protein_Domain |
| Ice Nucleation Protein(INP) | BBa_K2552003 | Coding |
| INP-Oligo Peptide T-1 | BBa_K2552004 | Coding |
| Ompa-Oligo Peptide T-1 | BBa_K2552005 | Coding |
| Ompa-Oligo Peptide T-2 | BBa_K2552006 | Coding |
| Pyear-azurin | BBa_K2552007 | Device |
| Ompa-Oligo peptide T-1-Pyear-azurin | BBa_K2552008 | Device |
Reference
Liu, R., Li, X., Xiao, W., & Lam, K. S. (2017). Tumor-targeting peptides from combinatorial libraries. Advanced drug delivery reviews, 110, 13-37.
