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pA7-GFP-Profilin 3

Sequence and Features

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Origin

Synthesized by the company and constructed by the team.

Properties

Fusion expression of protein Profilin3-GFP.

Usage and Biology

The pA7 plasmid vector serves as a carrier for the expression of fusion proteins, particularly well-suited for the production of GFP fusion proteins in prokaryotic cells such as E. coli. This vector features a multi-cloning site (MCS), which enables researchers to insert target genes, thereby facilitating the fusion of the target protein with GFP for subsequent expression. Such design allows for visualization and tracking of the target protein through GFP, aiding in investigations into its localization, expression levels, and dynamic behavior within cellular environments. Typically, the pA7 plasmid incorporates a robust promoter—such as lac or tac—to enhance expression efficiency and may include an antibiotic resistance gene serving as a selection marker to identify transformed bacterial strains. Furthermore, this vector may also possess a cleavable tag sequence that permits removal of GFP by specific proteases (e.g., TEV protease) at later stages, thus yielding purified target proteins. The strategic design of this vector not only streamlines protein purification processes but also facilitates functional analysis of proteins.

Cultivation and Purification

Figure 1. Plasmid map of pA7-GFP-PFN3.

The vector PA7 originates from a non-respiratory clinical isolate of Pseudomonas aeruginosa from Argentina, later linked with GFP. It is used for protein expression in plants, with a plant expression vector that includes a 35S promoter and ampicillin resistance. It is usually cultivated in a DH5α E. coli strain at 37°C. It was chosen to measure the protein expression of PFN3.

Figure 2. PCR amplification of the fragment used for plasmid construction.

We constructed pA7-GFP-PFN3 using homologous recombination. The pA7-GFP-PFN3 sequence was amplified by PCR, with a length of 396 bp.

Figure 3. Growth of plasmid pA7-GFP-PFN3 transformed bacteria on LB agar plates.

Then, the target gene sequence including Profilin 3 was inserted. It was reconstructed through homologous recombination. To incubate and culture the reassembled plasmid overnight, it was diluted and spread out onto an LB agar plate. In Figure 3 shown above, the growth of pA7-GFP-Profilin 3 was significant.

Measurement and Characterization

Figure 4. Colony PCR verification of PA7-PFN3.

Single colonies from each of the LB agar plates were taken and amplified through PCR. Multiple samples were taken from each of the plates to ensure that even if an error occurs, other samples could cover it.

Figure 5. Sanger sequencing map of PA7-GFP-PFN3.

The sequencing results of the reconstructed plasmid PA7-GFP-PFN3 were within the expected parameters, indicating no significant deviations. The sequence matched the designed structure, confirming the successful integration of the target gene into the plasmid. By transforming the reconstructed plasmid into the protoplasm of Arabidopsis thaliana and observing the changes in GFP fluorescence intensity and PFN3 gene expression in the protoplasm after the addition of siRNA that inhibited the expression of this protein, the effectiveness of siRNA was verified.

Figure 6. Enzymatic hydrolysis solution for protoplasts.

Extracting protoplasts from Arabidopsis thaliana is the first step. Protoplasts are isolated from healthy, pest-free Arabidopsis leaves by cutting young leaves into small pieces under sterile conditions and suspending them in a digestive solution containing cellulase and pectinase. This enzyme hydrolytically degrades the cell wall, releasing protoplasts, which are then cultured with gentle agitation for thorough digestion. Successful enzymatic hydrolysis is essential for efficient extraction and subsequent manipulation of protoplasts.

Figure 7. Observation under fluorescence microscope.

After isolating protoplasts from Arabidopsis, we transformed three RNAi targets specifically for the PFN gene: PA7-PFN3+RNAi-A, PA7-PFN3+RNAi-B, and PA7-PFN3+RNAi-C. Microscopic observation showed that GFP fluorescence was weak after transformation, which may indicate that the construct failed to express successfully or was suppressed by RNAi. Bright-field microscopy revealed that most protoplasts were round, indicating their healthy state.

Figure 8. The Profilin 3 mRNA transcription level in treated and untreated protoplasts.

The siRNA sequence Profilin 3-A successfully reduced the mRNA levels of profilin expression in injected tobacco leaf cells to approximately 0.5 times that of unregulated cells, demonstrating the evident improvements created by our therapy. However, the other two siRNA sequences were not similarly successful; in contrast, the mRNA levels remained largely unchanged compared to the baseline.

Reference

1. Kwon Y. J., Kim S. H., Lee S. G., Lee S. Y., & Kim T. H. (2001). Construction of a novel expression vector system for enhanced production of recombinant proteins in Escherichia coli. Journal of Industrial Microbiology & Biotechnology, 27(5), 291-296. [1](https://doi.org/10.1038/sj.jimb.7000919)
2. Buchholz F., & Prehn S. (2002). The Gateway System: Applications for protein expression and tagging. Current Opinion in Biotechnology, 13(6), 553-558. [2](https://doi.org/10.1016/S0958-1669(02)00362-9)
3. He X., & Wang X. (2005). Expression vectors and systems for recombinant protein expression. In Methods in Molecular Biology, Vol. 297, Protein Expression Systems. Humana Press.