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中国科学院生物物理研究所高璞团队揭示RADAR抗噬菌体超分子组装的分子基础。这一研究成果于2023年2月9日在线发表在国际学术期刊《细胞》上。

研究人员表示，腺苷-肌苷RNA编辑被认为参与一种称为RADAR的细菌抗噬菌体防御系统。RADAR含有腺苷三磷酸酶（RdrA）和腺苷脱氨酶（RdrB）。

研究人员报道了RdrA、RdrB，以及目前鉴定的RdrA-RdrB复合物存在或不存在RNA和ATP的冷冻电镜结构。RdrB组装成一个十二聚体笼，催化袋向外，而RdrA采用自抑制十四聚体和活化能力的七聚体环。结构和功能数据表明，RNA通过RdrA环的底部装载，并沿着其内部通道进行易位，这一过程可能与ATP结合状态相结合。有趣的是，多达12个RdrA环可以连接一个RdrB笼，在脱氨酶催化袋和RNA易位通道之间精确对齐，这表明RNA易位和脱氨酶的耦合。这些数据揭示了通过超分子组装的酶偶联和抗噬菌体防御的一个有趣机制。

附：英文原文

Title: Molecular basis of RADAR anti-phage supramolecular assemblies

Author: Yina Gao, Xiu Luo, Peipei Li, Zhaolong Li, Feng Ye, Songqing Liu, Pu Gao

Issue&Volume: 2023-02-09

Abstract: Adenosine-to-inosine RNA editing has been proposed to be involved in a bacterial anti-phagedefense system called RADAR. RADAR contains an adenosine triphosphatase (RdrA) andan adenosine deaminase (RdrB). Here, we report cryo-EM structures of RdrA, RdrB, andcurrently identified RdrA-RdrB complexes in the presence or absence of RNA and ATP.RdrB assembles into a dodecameric cage with catalytic pockets facing outward, whileRdrA adopts both autoinhibited tetradecameric and activation-competent heptamericrings. Structural and functional data suggest a model in which RNA is loaded throughthe bottom section of the RdrA ring and translocated along its inner channel, a processlikely coupled with ATP-binding status. Intriguingly, up to twelve RdrA rings candock one RdrB cage with precise alignments between deaminase catalytic pockets andRNA-translocation channels, indicative of enzymatic coupling of RNA translocationand deamination. Our data uncover an interesting mechanism of enzymatic coupling andanti-phage defense through supramolecular assemblies.

DOI: 10.1016/j.cell.2023.01.026

Source: https://www.cell.com/cell/fulltext/S0092-8674(23)00056-9