黑曲霉蛋白分泌途径中脂类压力诱导未折叠蛋白应答机制的研究

黑曲霉高效分泌蛋白，是生产食品酶的理想宿主菌。但非真菌来源的食品酶产量却相当低，其瓶颈在于分泌途径内质网中蛋白的折叠和修饰。异源蛋白表达、化学物刺激等导致分泌途径中非折叠蛋白积累而形成内质网压力，并诱导UPR信号机制，激活与蛋白分泌途径相关的基因表达，加强细胞蛋白折叠能力。近年的研究显示UPR信号机制具有应答脂类代谢信号调控的功能，蛋白分泌途径由有膜细胞器如内质网、高尔基体、囊泡等组成，内质网是脂类合成的主要场所，脂类动态平衡与蛋白质动态平衡控制对蛋白分泌途径有着同样的重要作用。本项目针对黑曲霉中脂类成分平衡失调而产生脂类压力，并单独诱导UPR信号机制及其如何调控脂类合成和蛋白质折叠质量的机制等科学问题而提出，本项目基于完善黑曲霉磷脂合成途径调控机制的基础上，构建磷脂合成功能缺陷株，改变脂类成分平衡形成脂类压力，研究其单独诱导UPR机制以及对蛋白分泌途径的调控机制，并促进异源食品酶生产。

Aspergillus niger has received increasing attention as a host for Food enzymes production due to its capacity to secrete large amounts of proteins. But production levels of non-fungal recombinant proteins are generally lower than those of homologous proteins with likely bottlenecks at protein quality control mechanisms in the endoplasmic reticulum(ER) of the secretory pathway. The expression of heterologous proteins and the chemicals stimulation result in the accumulation of unfolded proteins to induce the unfolded protein response (UPR). And UPR can detects misfolded proteins in the ER and activates transcription of genes that facilitate proper protein folding. Recent, UPR also upregulates key phospholipid synthesis genes, thus providing a potential mechanism to respond to lipid stress. And the proteins secretory pathway consists of organelles with membranes such as ER, Golgi apparatus and vesicles. It is the important roles in the functions of the protein secretory pathway that the equilibrium are controlled between the lipid and the protein homeostasis. This project want to answer the following scientific questions the UPR mechanism induced by the lipid stress of ER and its regulation mechanism to control the lipid and the protein homeostasis in the filamentous fungi A. niger. Based on our studies on the transcription regulation of phospholipid synthesis in A. niger, we will build the function gene defective strains to change the equilibrium of lipids to induce UPR independently. Furthermore, we want to explore the lipid-dependent regulation of UPR to control the equilibrium between the lipid and the protein homeostasis with the improvement of the expression of heterologous food enzymes.