海洋微藻碳酸酐酶研究进展

Research progress on carbonic anhydrase of marine microalgae

海洋藻类通过光合作用同化CO_(2)和H_(2)O,贡献了全球初级生产力的46%,对其固碳机制的探索研究意义重大.受限于水环境中的无机碳理化性质以及固碳关键酶对底物CO_(2)的低亲和力,海洋光合藻类演化出碳浓缩机制(CCM)以提高固碳效率.碳酸酐酶(CA)是CCM中的关键酶,能催化HCO_(3)-与CO_(2)的可逆转化.得益于近年来藻类基因组学和转录组学的快速发展,藻类CA的鉴定、生理特性及其与CCM的关系研究深入到分子水平,人们基于多样性特征,包括不同亚细胞定位、基因序列多样性、蛋白结构多样性以及功能多样性,将CA划分为不同家族.本文综述不同光合微藻的CA基因家族多样性、生理活性及其在CCM中作用的研究进展,提出未来需进一步拓展CA基因家族在不同微藻CCM中生理功能多样性与环境响应机制的研究,包括:加强海水升温与酸化、大洋环境中金属离子共限制对微藻CA活性及CCM的影响等方面的研究;在具有重要生态意义与珊瑚共生的虫黄藻中深入开展CA研究;分析CA结合不同金属辅因子的生态学影响;并对微藻CA在全球气候变化以及“碳中和”背景下的应用前景进行展望.

Marine algae assimilate CO_(2)and H_(2)O through photosynthesis,which contributes to 46%of global primary production and plays a prominent role in carbon fixation.Limited by the physicochemical properties of inorganic carbon in the aquatic environment and the low affinity of key enzymes of carbon sequestration for the substrate CO_(2),marine photosynthetic algae have evolved carbon concentration mechanism(CCM)to enhance carbon sequestration.Carbonic anhydrase(CA)is the key enzyme of CCM that catalyzes the interconversion between HCO 3-and CO_(2).With the advancement of algae genomics and transcriptomics,the identification and physiological characterization of algal CAs and their association with CCM have been conducted at the molecular level.Classification of the CA family is based on diverse characteristics,including different subcellular localization,gene sequence diversity,protein structure diversity and functional diversity.In this review,we summarize the research progress on CA gene family diversity,physiological activity and their functions in CCM in different photosynthetic microalgae.We suggest that further research should focus on the physiological diversity of CA gene family and environmental response mechanisms in CCM of different microalgae,including:strengthening the research on the effects of ocean warming,acidification,and metal ion co-limitation in the oceanic environment on CA activity and CCM mechanism;conducting the in-depth study of CA in the ecologically important dinoflagellate Symbiodiniaceae,which form symbiotic relationships with corals;analyzing the ecological implications of the diversified metal cofactor possessed by CA;and prospecting the practical application of CA in the context of global change and carbon neutrality.