蛋白A信号肽引导的E.coli外泌高表达异源蛋白

利用葡萄球菌ｐｒｏｔｅｉｎ Ａ信号序列（ＳＰＡ），我们构建了不同启动子控制的分泌表达质粒。经表达研究，获得了可控性好、表达量高的ＰＬ启动子控制的分泌表达载体。通过菌种的筛选、培养条件和诱导条件的摸索，获得了能将表达产物的绝大部分分泌到培养液中的大肠杆菌高效外泌表达系统，外泌表达量可达１００ｍｇ／Ｌ（菌浓度为１Ａ６００／ｍｌ）以上，如此高的分泌表达量尚未见文献报道。利用该系统成功、高效地外泌表达了ｐ

High-level Excretion of Heterologous Proteins from E. coli Directed by Protein A Singal Peptide

Several plasmids were constructed by inserting the staphylococcal Protein A signal-encoding seqnence at the 5'-terminal of recombinant genes or DNA fragments controlled under various promoters, and the study of secretion expression was carried out. High level products which were secreted to the reriplasmic space were observed in E.coli harboring plasmids controlled by PL promoter.By optimizing the expression conditions such as the E. coli host, medium, temperature, and PH,some recombinant proteins could be secreted to the culture medium at a level of 100mg/L (with the concentration of bacteria at 1 A600/ml). With this excretion system, four recombinant proteins, protein A, its EDA (PA-EDA) and ABC (PA-ABC) domains, and its fusion Protein with insulin-like growth factor I (PA-IGF-I), were highly expressed and successfully excreted from E. coli to themedium. The N-terminal analysis of these proteins showed that the signal peptides were processed correctly.