Cell-penetrating peptides (CPPs) are short peptides that can cross cell membranes. CPPs enable the delivery of biomolecules into cells and can act as drug-delivery vectors. Because recombinant production of CPPs as fusions to protein "cargo" leads to low yields for some CPP-cargo fusions, approaches to enhance the recombinant expression of peptide-cargo fusions need to be identified. We optimized expression conditions in Escherichia coli for fusions of CPPs (SynB, histatin-5, and MPG) to the cargo proteins biotin carboxyl carrier protein, maltose-binding protein, and green fluorescent protein. We used Western blotting to evaluate induction temperatures of 37, 30, and 20°C, and induction times of 6, 10, and 24 h. Glutathione-S-transferase was incorporated as a fusion partner to improve expression. In general, expression at 37°C for 6 and 10 h led to the highest levels of expression for the different CPP-cargo constructs. The improvements in expression of CPP-cargo fusions will allow higher yields of CPP-cargo fusions for studies of their translocation into cells.

中文翻译：

---

细胞穿透肽融合蛋白的表达。

细胞穿透肽（CPPs）是可以穿过细胞膜的短肽。CPP使生物分子能够传递到细胞中，并可以充当药物传递载体。由于重组生产CPP作为与蛋白质“货物”的融合体会导致某些CPP-货物融合体的低收率，因此，需要确定增强肽-货物融合体重组表达的方法。我们优化了大肠杆菌中CPP（SynB，histatin-5和MPG）与货物蛋白生物素羧基载体蛋白，麦芽糖结合蛋白和绿色荧光蛋白融合的表达条件。我们使用蛋白质印迹法评估了37、30和20°C的诱导温度，以及6、10和24 h的诱导时间。谷胱甘肽-S-转移酶作为融合伴侣并入以改善表达。一般来说，在37°C的条件下表达6小时和10小时导致不同CPP货物构建体的最高表达水平。CPP-货物融合体表达的改进将允许更高的CPP-货物融合体产量用于研究其向细胞内的转运。