Li Cheng, Lin Ying, Huang Yuanyuan, Liu Xiaoxiao, Liang Shuli
Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, P. R. China.
PLoS One. 2014 Dec 9;9(12):e114728. doi: 10.1371/journal.pone.0114728. eCollection 2014.
Phytase expressed and anchored on the cell surface of Pichia pastoris avoids the expensive and time-consuming steps of protein purification and separation. Furthermore, yeast cells with anchored phytase can be used as a whole-cell biocatalyst. In this study, the phytase gene of Citrobacter amalonaticus was fused with the Pichia pastoris glycosylphosphatidylinositol (GPI)-anchored glycoprotein homologue GCW61. Phytase exposed on the cell surface exhibits a high activity of 6413.5 U/g, with an optimal temperature of 60°C. In contrast to secreted phytase, which has an optimal pH of 5.0, phytase presented on the cell surface is characterized by an optimal pH of 3.0. Moreover, our data demonstrate that phytase anchored on the cell surface exhibits higher pH stability than its secreted counterpart. Interestingly, our in vitro digestion experiments demonstrate that phytase attached to the cell surface is a more efficient enzyme than secreted phytase.
表达并锚定在毕赤酵母细胞表面的植酸酶避免了蛋白质纯化和分离中昂贵且耗时的步骤。此外，带有锚定植酸酶的酵母细胞可用作全细胞生物催化剂。在本研究中，丙二酸柠檬酸杆菌的植酸酶基因与毕赤酵母糖基磷脂酰肌醇（GPI）锚定糖蛋白同源物GCW61融合。暴露在细胞表面的植酸酶表现出6413.5 U/g的高活性，最适温度为60°C。与分泌型植酸酶的最适pH为5.0不同，细胞表面呈现的植酸酶最适pH为3.0。此外，我们的数据表明，锚定在细胞表面的植酸酶比其分泌型对应物表现出更高的pH稳定性。有趣的是，我们的体外消化实验表明，附着在细胞表面的植酸酶比分泌型植酸酶更高效。
