蝶蛹金小蜂热激蛋白家族基因表达与热保护功能.doc

蝶蛹金小蜂基因表达Pteromalus puparum热激蛋白家族的分子伴侣功能，本研究对来自该寄生蜂的Pphsp90，Pphsp70，Pphsc70，Pphsp60，Pphsp40和Pphsp20等蛋白的基因在大肠杆菌Escherichia coli BL21菌株中进行了过表达。结果表明：除Pphsp40外，其余5个基因均得到高效表达，且表达的重组热激蛋白在高温下（80℃）具可溶性与热稳定性。其中，Pphsp20与Pphsp90在大肠杆菌中的表达显著提高了高温下（50℃，1 h）细胞的存活率。离体活性实验证实，利用纯化的融合蛋白Pphsp20可减少高温下荧光素酶的聚集现象。据此认为，Pphsp20与Pphsp90均具有大肠杆菌细胞的热保护功能，但Pphsp20可以单独发挥作用，而Pphsp90可能需其他因子协同作用才有保护活性。 关键词: 蝶蛹金小蜂；热激蛋白；基因表达；蛋白热稳定性；蛋白纯化 Prokaryotic Expression and Thermo-protective Function of Heat Shock Proteins from Pteromalus puparum(Hymenoptera: Pteromalidae) Wang Huan (Shanghai Vocational and Technical College of Agriculture and Forestry, Songjiang, Shanghai, 210016) Abstract: Acting as molecular chaperones, heat shock proteins (Hsps) could help fixing denatured proteins and preventing aggregation of other proteins. In order to further understand the function of molecular chaperone of Hsp families in the parasitoid Pteromalus puparum, Pphsp90, Pphsp70, Pphsc70, Pphsp60, Pphsp40 and Pphsp20 from this parasitoid were over-expressed in Escherichia coli. The results showed that five genes except Pphsp40 were highly expressed and these expressed recombinant Pphsps were soluble and stable under high temperature (80℃). In vivo experiments, Pphsp20 and Pphsp90 significantly increased survival rate of E. coli cells under high temperature (50℃, 1 h). In vitro protection study verified that only purified recombinant Pphsp20 could reduce the aggregation of luciferase under high temperature. The results suggest that both Pphsp20 and Pphsp90 may be involved in thermo-protective role in E. coli, and Pphsp20 may work independently while Pphsp90 requires the cooperation with other cofactors. Key words: Pteromalus puparum，heat shock proteins，gene expression，protein thermo-stability，protein purification 热激蛋白（heat shock proteins，Hsps）是普遍存在于原核和真核生物中的一类高度保守的蛋白。Feder和Hofmann（1999）根据序列相似性和蛋白分子量大小将Hsps分为Hsp110，Hsp100，Hsp90，Hsp70，Hsp60，Hsp40，Hsp10和sHsp 8个家族。尽管不同生物体同一Hsp家族之间有高度序列相似性，但不同Hsps家族之间其序列无明显的相似性，功能上也不尽相同。 充当分子伴侣是Hs