Part:BBa_K1151001
Improved by Fudan iGEM 2024
This part is called Hpn for short. The His-rich putative nickel storage protein plays a crucial role in nickel detoxification. Hpn may sequester metals that accumulate internally via a passive equilibrium mechanism (from a high external metals environment).[1] The Hpn working with BBa_K5115000 (RcnR_C35L) and BBa_K5115050 (MTA), together they can trick bacteria to aggressively absorb nickel ion from the environment, as well as reducing the harm nickel brings to the bacteria.
Improved part
Our improved part is BBa_K5115036 (Ribozyme + RBS + Hpn + stem-loop). We wrapped Hpn coding sequence with ribozyme-assisted polycistronic co-expression system (pRAP) sequences. By inserting BBa_K4765020 before CDS, the RNA of Twister ribozyme conduct self-cleaving in the mRNA.[2] To protect the mono-cistron mRNA from degradation, a stem-loop structure is placed at the 3' end of CDS.[3] In 2023, we extensively tested various stem-loops using BBa_K4765129.
As for the ribosome binding sequence (RBS) after the ribozyme and before the CDS, we used T7 RBS, from bacteriophage T7 gene 10.[4] It is an intermediate strength RBS according to our 2022 results, which allows us to change it to a weaker J6 RBS or a stronger B0 RBS if needed.
Histidine-rich metal-binding protein
So called for emphasize its origins in Helicobacter pylori and its avidity for nickel. Consisting of 60 aminoacids, the protein is rich in histidine (28 residues, 46.7 %) and contains short repeating motifs, it exists as an equilibration of multimeric forms in solution, with 20-mers (approx. 136 kDa) being the predominant species. Hpn can bind tightly and reversibly up to five Ni2+ ions per each monomer of 7 kDa in a pH-dependent manner (pH 7.4 ). In H. pylori play an important role in storing nickel required to the survival of the bacterium.
Boiling prep and digestion with restriction enzymes
Once inserted the gene coding for Hpn in a PSB1C3 plasmid (digestion and ligation), we transformed DH5a cells with the construct and then we recovered the ligated plasmid by boiling prep. We then proceeded with the digestion with EcoRI and PstI to check.
Figure 1: Digestion result of boiling prep plasmids.
PCR with VF2 and VR2 primers
Figure 2: PCR results.
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]
- ↑ Maier, R. J., Benoit, S. L., & Seshadri, S. (2007). Nickel-binding and accessory proteins facilitating Ni-enzyme maturation in Helicobacter pylori. Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine, 20(3–4), 655–664.
- ↑ Eiler, D., Wang, J., & Steitz, T. A. (2014). Structural basis for the fast self-cleavage reaction catalyzed by the twister ribozyme. Proceedings of the National Academy of Sciences, 111(36), 13028–13033.
- ↑ Liu, Y., Wu, Z., Wu, D., Gao, N., & Lin, J. (2022). Reconstitution of Multi-Protein Complexes through Ribozyme-Assisted Polycistronic Co-Expression. ACS Synthetic Biology, 12(1), 136–143.
- ↑ The T7 phage gene 10 leader RNA, a ribosome-binding site that dramatically enhances the expression of foreign genes in Escherichia coli. Olins PO, Devine CS, Rangwala SH, Kavka KS. Gene, 1988 Dec 15;73(1):227-35.
| n/a | Histidine-rich metal-binding protein |