苏云金芽胞杆菌分泌蛋白的鉴定及分析

Identification and Analysis of Secretory Proteins in Bacillus thuringiensis

研究苏云金芽胞杆菌(Bacillus thuringiensis,Bt)在生长发育过程中分泌蛋白的类型和含量,尤其是胞外蛋白酶,对于充分了解该菌的杀虫机理、扩大该菌的应用具有重要意义。通过制备Bt_HD73过渡期(transition phase)的分泌蛋白质样品,进行质谱检测并分析其分泌蛋白的种类、含量、功能和信号肽等。结果表明,Bt_HD73在过渡期初期有54种胞外蛋白质,其中酶类最多,占所有分泌蛋白的66.30%,且主要为蛋白水解酶;毒力蛋白次之,占所有分泌蛋白的14.53%。在54种分泌蛋白中,发现27种含有经典Sec型信号肽(Secretory signal peptide,Sec-type SP),信号肽的长度在24-40个氨基酸之间。因此,Bt_HD73产生分泌蛋白的能力较强,在过渡期可分泌大量酶类,尤其是蛋白水解酶。同时还建立了该菌株的信号肽库,包括27种具有引导外源蛋白分泌潜力的信号肽。

The study on Bacillus thuringiensis（Bt）secretory protein types and their contents,especially the extracellular proteases,is of great significance for fully understanding the insecticidal mechanism and expanding the application of this bacterium. In our research,thesecretory protein samples in the transition phase of BtHD73 were detected by mass spectrometry,then the types,contents,functions andsignal peptides of secretory proteins were analyzed. The results showed that BtHD73 secreted 54 kinds of extracellular proteins in transitionphase,and most of them were enzymes,accounting for 66.30% of all secretory proteins. Moreover,most of the enzymes were proteases,andthe followed was virulence protein,accounting for 14.53% of all secretory proteins. Among the 54 secretory proteins,27 proteins were foundto contain the classic Sec-type signal peptides,and the lengths were between 24 and 40 amino acid residues. Therefore,BtHD73 has a strongsecretory ability,and it can secrete large amounts of enzymes especially proteases in the transition phase. Concurrently,the signal peptidelibrary of this strain was established in this study,including 27 signal peptides with potential for guiding the secretion of heterologous proteins.