This work was supported by a grant from The National Natural Science Foundation of China (30670053)
为了获得高效的脂肪酶毕赤酵母表面展示系统,利用来自酿酒酵母絮凝素蛋白Flo1的N端874个氨基酸残基(FS)和C端的1 101个氨基酸残基(FL)作为锚定蛋白分别构建了2套载体系统.带有前肽的米黑根毛霉脂肪酶(ProRML)克隆到构建的2套展示载体中,使米黑根毛霉脂肪酶(RML)分别以N端锚定或C端锚定的方式实现在毕赤酵母细胞表面的展示.利用RML C端的Flag标签,通过流式细胞术和激光扫描共聚焦显微镜检测2套系统中RML在酵母表面的展示情况.研究发现,N端锚定于酵母表面的展示酶FSR以pNPC为底物时,水解活力达到了105.3 U/g,大约为C端锚定的展示酶FLR活力的2倍.同时FSR比FLR具有更宽的温度、pH作用范围和更好的热稳定性.与游离酶和固定化酶相比,展示酶FSR也表现出更为优良的热稳定性.结果提示,基于Flo1 N端锚定的展示系统更适合展示活性中心近C端的脂肪酶,推动了展示酶的进一步研究和开发.
To obtain a high efficiency Pichia pastoris cell surface display system, two new systems based on two different anchor proteins derived from Saccharomyces cerevisiae Flo1 protein (Flo1p) were constructed respectively. The N-terminal anchor system could make the foreign lipase displayed on the P. pastoris cell surface with its C terminus free by fusion with an anchor protein containing N-terminal flocculation functional domain of Flo1p (874 residues, FS) , which was able to adhere to the cell surface via noncovalent interaction with the mannan chain of the cell wall. Conversely, the foreign lipase can kept its N terminus free in another C-terminal anchor system, which utilizes a GPI-attachment signal domain located at C-terminal region of Flo1p (1 101 residues, FL) as anchor protein. Using these systems above, recombinant R. miehei lipase with a pro region (ProRML) , which had its active site near the C-terminus, was displayed on the P. pastoris cell surface, and two surface-displayed RML, named as FSR and FLR, were obtained. Cell-surface display of the RML via Fs or FL anchor system was confirmed by flow cytometer and laser scanning confocal microscope. A strong fluorescence was clearly observed in recombinant yeast cells harboring pKFSR( pKFS-RML), but no fluorescence was detected in the yeast cells harboring pKFLR(pKFL-RML) . The hydrolytic activity of FSR reached 105. 3 U/g·[dry cell weight] with p-Nitrophenyl caprylate (pNPC) as the substrate, which is 2 times as high as that of FLR. In addition, the cell-surface display systems based on FS or FL endowed the displayed RML with different enzymatic properties. The surface-displayed RML with its C-terminus free (FSR) showed a better catalytic performance at temperature, pH and thermostability than the surface-displayed RML with its N-terminus free (FLR) did. The results suggest that the surface display of RML based on FS anchor system is more promising and more effective, especially for N-terminal immobilization of target enzyme whose catalytic site is near the C terminus.
韩双艳,韩振林,林影,郑穗平.高效絮凝素毕赤酵母表面展示系统的构建[J].生物化学与生物物理进展,2010,37(2):200-207
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