Difference between revisions of "Part:BBa K4613024"

Revision as of 08:50, 12 October 2023

pQE-80L-T3-MCPA

The composite part was constructed to find an appropriate expression intensity to achieve balance between metabolic burden and detection efficiency. Moreover, we hope Mature Carboxypeptidase A (M-CPA), which can be found under https://parts.igem.org/Part:BBa_K4613013, can be expressed successfully in E. coli Nissle 1917 (EcN). We tried T5 lac promoter from pQE-80L.

We first cloned C3 into the pQE-80L, constructed pQE-80L-C3 and expressed the recombinant protein in E. coli BL21(DE3) using Terrific Broth medium and 2xYT medium.

After incubation at 20℃ overnight or 37℃ for 4h, respectively, we found that C3 expression level in the supernatant was very low, and no obvious bands were found at 54.5 kDa As shown in Fig 1(b-c).

Fig. 1 Results of pQE-80L-C3. a. The plasmid map of pQE-80L-C3. b.SDS-PAGE analysis of protein expression trials in E. coli BL21(DE3) cultured in Terrific Broth medium overnight using pQE-80L-C3. The temperature was 20℃. Lane M: protein marker. Lane 1: induced total protein. Lane 2: precipitation. Lane 3: supernatant. c. SDS-PAGE analysis of protein expression trials in E. coli BL21(DE3) cultured in Terrific Broth medium for 4 hours using pQE-80L-C3. The temperature was 37℃. Lane M: protein marker. Lane 1: induced total protein. Lane 2: precipitation. Lane 3: supernatant.

SpyTag and SpyCatcher are a pair of reactive protein partners that can spontaneously react to reconstitute the intact folded CnaB2 domain under mild conditions. Hydrophilic elastin-like polypeptides (ELPs) composed of tandem pentapeptides of the form (VPGXG)(n) (where X may be any amino acid except proline) always serve as versatile model systems for biomaterials.

We used ELPs as the backbone of the monomers. Each monomer was fused with 3 SpyTags or 3 SpyCathcers. The polymerization between these two types of monomers can proceed efficiently under multiple conditions. We linked degrading enzymes (M-CPA/ADH3) into the SpyTag monomer to immobilize the enzyme and increase the stability of degrading enzymes.

Fig. 2 Formation of Spy Network. (a)Gene circuit. (b)The polymerization between these two types of monomers.

To verify the combination between T3 and C3, we engineered bacteria expressing T3-YFP (SpyTag-ELPs-SpyTag-ELPs-SpyTag-YFP) and bacteria expressing C3 (SpyCathcer-ELPs-SpyCathcer-ELPs-SpyCathcer). The constructed plasmids were transformed into E. Coli BL21 (DE3) and recombinant proteins were expressed using LB medium.

Purified T3-YFP and C3 were subjected to reactions under predefined time and temperature radients. The proteins after reaction were validated by electrophoresis on polyacrylamide gels (SDS-PAGE), followed by Coomassie brilliant blue staining. A distinct target band can be observed at 130 kDa, demonstrating that T3-YFP (62.4 kDa) and C3 (54.5 kDa) are capable of forming the Spy Network (Fig.3).This reaction can occur at a variety of temperatures and has good reaction characteristics.

Fig. 3 Verification of the fabrication between T3-YFP and C3. Lane1:T3-YFP. Lane2:C3. M: Marker. Lane3: T3-YFP and C3(4℃,8h).Lane4: T3-YFP and C3(4℃,3h). Lane5: T3-YFP and C3(4℃,1h). Lane6: T3-YFP and C3(25℃,8h).Lane7: T3-YFP and C3(25℃,3h).Lane8: T3-YFP and C3(25℃,1h).Lane9: T3-YFP and C3(37℃,8h).Lane10: T3-YFP and C3(37℃,3h). Lane11: T3-YFP and C3(37℃,1h).

Reference

1. Dai Z, Yang X, Wu F, et al.Living fabrication of functional semi-interpenetrating polymeric materials[J].Nat Commun,2021, 12 (1): 3422.
2. Zakeri B, Fierer J O, Celik E, et al.Peptide tag forming a rapid covalent bond to a protein, through engineering a bacterial adhesin[J].Proc Natl Acad Sci U S A,2012, 109 (12): E690-7.
3. Reddington S C, Howarth M.Secrets of a covalent interaction for biomaterials and biotechnology: SpyTag and SpyCatcher[J].Curr Opin Chem Biol,2015, 29: 94-9.
4. Xiong L, Peng M, Zhao M, et al.Truncated Expression of a Carboxypeptidase A from Bovine Improves Its Enzymatic Properties and Detoxification Efficiency of Ochratoxin A[J].Toxins (Basel),2020, 12 (11).

Sequence and Features