In vitro assembly of the bacterial actin protein MamK from ＇Candidatus Magnetobacterium casensis＇ in the phylum Nitrospirae

作     者：Aihua Deng Wei Lin Nana Shi Jie Wu Zhaopeng Sun Qinyun Sun Hua Bai Yongxin Pan Tingyi Wen 

作者机构：CAS Key Laboratory of Pathogenic Microbiology and Immunology Institute of Microbiology Chinese Academy of Sciences Beijing 100101 China Biogeomagnetism Group Paleomagnetism and Geochronology Laboratory Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China University of Chinese Academy of Sciences Beijing 100049 China 

出 版 物：《Protein & Cell》 (蛋白质与细胞（英文版）)

年 卷 期：2016年第7卷第4期

页      面：267-280页

核心收录：

学科分类：0710[理学-生物学] 071001[理学-植物学] 1007[医学-药学(可授医学、理学学位)] 100705[医学-微生物与生化药学] 07[理学] 071005[理学-微生物学] 10[医学] 

基　　金：ACKNOWLEDGEMENTS The authors would like to thank Rongcheng Han  Yabing Liu and Xiaolan Zhang for assistance with the fluorescence microscopy  and Jingnan Liang for assistance with transmission electron microscopy. This work was supported by the grants from the National Natural Science Foundation of China (Grants Nos. 31300065 and 41330104) and the Youth Innovation Promotion Association CAS 

主　　题：magnetotactic bacteria Nitrospirae,bacterial actin MamK assembly mechanism 

摘      要：Magnetotactic bacteria （MTB）, a group of phylogeneti- cally diverse organisms that use their unique intracellular magnetosome organelles to swim along the Earth＇s magnetic field, play important roles in the biogeochemical cycles of iron and sulfur. Previous studies have revealed that the bacterial actin protein MamK plays essential roles in the linear arrangement of magnetosomes in MTB cells belonging to the Proteobacteria phylum. However, the molecular mechanisms of multi- ple-magnetosome-chain arrangements in MTB remain largely unknown. Here, we report that the MamK filaments from the uncultivated ＇Candidatus Magnetobacterium casensis＇ （Mcas） within the phylum Nitrospirae polymerized in the presence of ATP alone and were stable without obvious ATP hydrolysis-mediated disassembly. MamK in Mcas can convert NTP to NDP and NDP to NMP, showing the highest preference to ATP. Unlike its Magnetospirillum counterparts, which form a single magnetosome chain, or other bacterial actins such as MreB and ParM, the polymerized MamK from Mcas is independent of metal ions and nucleotides except for ATP, and is assembled into well-ordered filamentous bundles consisted of multiple filaments. Our results suggest a dynamically stable assembly of MamK from the uncultivated Nitrospirae MTB that synthesizes multiple magnetosome chains per cell, These findings further improve the current knowledge of biomineralization and organelle biogenesis in prokaryotic systems.