Difference between revisions of "Part:BBa K5398020:Experience"

Revision as of 06:15, 30 September 2024

This experience page is provided so that any user may enter their experience using this part.
Please enter how you used this part and how it worked out.

Applications of BBa_K5398020

In order to obtain proteins with adhesive properties, we used the pET-SUMO vector to express TRn4-mfp5 ( BBa_K5398020) ). We tried different strategies for TRn4-mfp5 protein production and purification and tested its function.

Characterization

In order to obtain proteins, test suitable expression conditions, and evaluate the function of TRn4-mfp5, we chose three different expression vectors (Fig. 3)—pET-28a(+), pET-SUMO, and pET-21a(+)—and tried different strategies for TRn4-mfp5 protein production and purification.

Fig. 1 | Three different vectors used in protein expression.

a. The plasmid map of pET-28a(+)-His-SUMO-TRn4-mfp5; b. The plasmid map of pET-SUMO-TRn4-mfp5; c. The plasmid map of pET-21a(+)-TRn4-mfp5.

Fig. 2 | Comparison of fusion protein expression in different temperature use vector pET-21a(+).

Lanes 1-6 (LB 37°C 4 h): 1. Protein ladder; 2. total liquid (+IPTG); 3. supernatant (+IPTG); 4. precipitate (+IPTG); 5. total liquid (-IPTG); 6. supernatant (-IPTG); 7. precipitate (-IPTG); Lanes 8-13 (TB 16°C 20 h): 8. Protein ladder; 9. total liquid (+IPTG); 10. supernatant (+IPTG); 11. precipitate (+IPTG); 12. total liquid (-IPTG); 13. supernatant (-IPTG); 14. precipitate (-IPTG).

Fig. 3 | Comparison of fusion protein expression in LB and TB media use vector pET-21a(+).

1. Protein ladder; Lanes 2-7 (LB 16°C 20 h): 2. total liquid (+IPTG); 3. supernatant (+IPTG); 4. precipitate (+IPTG); 5. total liquid (-IPTG); 6. supernatant (-IPTG); 7. precipitate (-IPTG); Lanes 8-13 (TB 16°C 20 h): 8. Protein ladder; 9. total liquid (+IPTG); 10. supernatant (+IPTG); 11. precipitate (+IPTG); 12. total liquid (-IPTG); 13. supernatant (-IPTG); 14. precipitate (-IPTG).

Fig. 4 | Comparison of fusion protein expression in E. coli strains BL21(DE3) and Rosetta.

1. Protein ladder; Lanes 2-4 (BL21(DE3) LB 37℃ 4h) 2. total liquid (+IPTG); 3. supernatant (+IPTG); 4. precipitate (+IPTG); Lanes 5-7 (Rosetta LB 37℃ 4h) 5. total liquid (+IPTG); 6. supernatant (+IPTG); 7. precipitate (+IPTG).

Protein Purification

After considering both expression efficiency and practical experimental constraints, we decided to express the fusion protein at 37°C for 4 h in LB medium using the pET-SUMO-TRn4-mfp5 plasmid.</p>

As shown in Figures 4-6, the target protein was present in the pellet after cell lysis. Therefore, we denatured the pellet of the fusion protein TRn4-mfp5 with 8M urea overnight and renatured it through dialysis. This process resulted in some protein loss, as confirmed by SDS-PAGE analysis.

Consequently, we proceeded to purify the fusion protein TRn4-mfp5 using a Ni-NTA Gravity Column.

The target protein bands were present in lanes 4 to 7, indicating successful expression of the target protein, with a particularly strong band in the supernatant after denaturation (Fig. 7, lane 7). After purification, the target protein was mainly found in the 150 mM and 300 mM imidazole elution fractions.

Fig. 5 | SDS-PAGE of purified fusion protein TRn4-mfp5(35.4 kDa) uses vector pET-SUMO.

Lane 1: Protein - Binding buffer; Lane 2: 20 mM imidazole and 8 M urea elution; Lane 3: 50 mM imidazole and 8 M urea elution; Lane 4: 150 mM imidazole and 8 M urea elution; Lane 5: 300 mM imidazole and 8 M urea elution; Lane 6: 500 mM imidazole and 8 M urea elution; Lane 7: Supernatant; Lane 8: Impurities; Lane 9: Protein ladder.

To further confirm the expression of TRn4-mfp5, we performed a Western blot, which provided a clear and definitive conclusion, verifying the successful expression of the TRn4-mfp5 protein under the conditions mentioned above.

Fig. 6 | Western Blot of purified fusion protein TRn4-mfp5(35.4 kDa) uses vector pET-SUMO.

a. Western blot of the pre-expressed protein;b. Western blot after column purification of the supernatant following denaturation.

Adhesive test

We obtained protein samples of TRn4-mfp5 by freezedrying 24 h (Fig. 9). The final yield was about 25 mg/L bacterial culture.

Fig. 7 | The protein sample freeze-dried by a lyophilizer.

Next, we dissolved protein samples in Buffer A (10 mL 20 mM Tris pH8) to reach 0.3 mg/mL, and conduct adhesive ability tests on the fusion protein(Fig. 10). 200 μL of the protein solution was applied, and the pipette tip was placed on a plastic Petri dish lid. After incubation at 37°C for 8 h, the pipette tip successfully adhered.

Fig. 8 | Adhesive ability test of fusion protein on plastic surface

Viscosity Calculations

Surface Area Calculation:

The surface area of a 10 µl pipette tip with an inner diameter of 3.7 mm is calculated as:

Force Calculation:

The total mass is (5.951 + 0.448 × 3) grams, and the force is:

Adhesive Force Calculation:

The adhesive force produced by the protein is:

Adhesive Force per Milligram of Protein:

The adhesive force per milligram of protein is:

Reference

[1] Jung H., Pena-Francesch A., Saadat A, et al. Molecular tandem repeat strategy for elucidating mechanical properties of high-strength proteins[J]. PNAS, 2016, 113(23), 6478–6483.

[2] Zhang C, Wu B, Zhou Y, et al. Mussel-inspired hydrogels: from design principles to promising applications[J]. Chem Soc Rev, 2020, 49(3605): 3605-3637.