pET28a-sumo

Currently, such surfactants are mainly synthesized through expensive chemical methods. The efficient synthesis of surfactant-like peptides using biological methods has become an important research direction. This method is environmentally friendly and enables low-cost, efficient production. In this study, three novel surfactant peptides were designed and synthesized through biological methods and successfully expressed in vitro. Through the optimization of expression host, expression vector, and fermentation conditions, the optimal expression level is finally obtained. Furthermore, these surfactant-like peptides possess good surface activity and low critical micelle concentration. More importantly, they are pH responsive and can self-assemble into nanostructures in different solutions, which provides important research value for the production of new nanomaterials in the future.

In this study, combined with preliminary observation of fluorescence intensity and quantitative detection of fluorescence signals, the results showed that the vector pET28a-SUMO has a high expression level in BL21(DE3). Therefore, BL21 (DE3) was selected as the expression host to express the target peptide. SDS-PAGE results show that the vector pET-28a(+) cannot express (SP I)₁₅, while the vector with fusion tags (SUMO, GST, fluorescent protein CLC I) could form a fusion protein with (SP I)₁₅, which promoted the expression of (SP I)₁₅. The fusion protein in lane 2 accounted for 46.2% of the total bacterial protein, indicating that the SUMO tag can more effectively promote the expression of the target peptide. Therefore, pET28a-SUMO was selected for expression and subsequent optimization experiments.

Figure 1. Effects of different expression vectors and host cells on the expression of peptides. (a) Fluorescence intensity of (SP I)₁₅ in different host cells. 1: Rosetta (DE3), 2: BL21 (DE3), 3: BL21 (DE3) plysS. (b) SDS-PAGE of (SP I)₁₅ expressed in different vectors, lane 1: control, lane 2: pET28a-SUMO-(SP I)₁₅, lane 3: pET28a-CLC I-(SP I)₁₅, lane 4: pT7-GST-His- (SP I)₁₅, lane 5: pET28a-(SP I)₁₅. (Meng, Shujuan, et al., 2022)