镉结合蛋白CADR在莱茵衣藻细胞表面的展示及应用

Surface display and application of cadmium-binding protein CADR on the cell wall of Chlamydomonas reinhardtii

摘要:

在检测和修复环境中重金属如镉污染时，藻类被证实具有作为高效生物吸附材料的潜力。本研究旨在利用细胞表面展示技术在莱茵衣藻细胞壁表达镉结合蛋白CADR，提高衣藻对镉的吸附性能。首先，采用golden gate技术构建转化载体PET-X-CADR，通过细胞壁蛋白GP1将CADR锚定至细胞壁。同时利用融合标签YFP的荧光信号进行高通量筛选，得到3株CADR蛋白高表达且定位于细胞壁的工程藻株。生理实验结果表明，细胞壁展示CADR蛋白并不影响工程藻株在低于200μmol/L镉浓度下的生长；在200 μmol/L镉浓度下，CADR工程藻株的生长速度是野生型的3倍，表明CADR工程藻株对镉有更高的耐受性。运用配子型裂解酶GLE处理藻细胞分离野生型和工程藻株细胞壁，并比较其中镉的含量，结果显示工程藻株的细胞壁对镉吸附能力提升了33%。本研究为利用藻类治理环境中镉污染特别是从环境中回收重金属提供了新的思路。

Abstract:

Algae has been proven to have the potential to be efficient biosorbents in the detection and remediation of heavy metal pollution such as cadmium in the environment. This study aims to enhance the cadmium adsorption capacity of Chlamydomonas reinhardtii by expressing the cadmium-binding protein CADR on the cell wall by the surface display technology. Firstly, the golden gate technique was employed to construct the transformation vector PET-X-CADR, which anchored CADR to the cell wall with the cell wall protein GP1. The high-throughput screening with the fluorescence signal of the fusion tag YFP resulted in three engineered algal strains with high expression of CADR on the cell wall. Physiological experiments demonstrated that the CADR displayed on the cell wall did not affect the growth of the engineered algal strains exposed to cadmium with the concentration below 200 μmol/L. In the presence of 200 μmol/L cadmium, the growth rates of CADR-engineered algal strains were three times as that of the wild-type, indicating stronger tolerance of the CADR-engineered algae to cadmium. The protein lyase GLE released during the mating of Chlamydomonas was used to isolate the cell walls of wild-type and engineered strains, the cadmium content of which was compared. The results showed that the cell wall of the engineered strain exhibited an increase of 33% in cadmium adsorption capacity. This study gives insights into the application of algae in the management of cadmium pollution in the environment, especially in the recycling of heavy metals from the environment.