植物monellin甜蛋白基因的细菌化改造合成及其在大肠杆菌中的表达

根据西非植物Dioscoreophyllum cumminisii果实中分离到的monellin甜蛋白的氨基酸序列，首次按照细菌优化密码子，人工合成了全长294bp的monellin甜蛋白基因。克隆后序列分析表明，所获得基因与设计相符。构建了该基因的表达载体pGESP9。经42℃诱导表达，发现所合成甜蛋白基因可在大肠杆菌BL21中高效表达，表达量占菌体可溶性蛋白的22.8%。分离纯化monellin，经测定其甜度是相同重量蔗糖的1100倍，且甜味纯正持久。

Synthesis of a Bacterial-like Plant Monellin Gene and Its Expression in E.coli

According to the amino acid sequence of monellin isolated from the fruit of Western African plant Dioscoreophyllum Cumminisii., a single chain 294bp monellin sweet protein gene was synthesized using E. colt biased codons. After sequencing, an expression vector pGESP9 harboring the gene was constructed and was transferred into E. coli BL21. Heat inducing expression showed that the sweet protein could be produced at a high level: 22. 8% of the E. coli soluble protein. The flavorful monellin was 1100 times sweeter than sucrose on a same weight basis.