Solution Structures of Cytosolic RNA Sensor MDA5 and LGP2 C-terminal Domains IDENTIFICATION OF THE RNA RECOGNITION LOOP IN RIG-I-LIKE RECEPTORS
Solution Structures of Cytosolic RNA Sensor MDA5 and LGP2 C-terminal Domains IDENTIFICATION OF THE RNA RECOGNITION LOOP IN RIG-I-LIKE RECEPTORS
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DOI：
10.1074/jbc.m109.007179
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发表时间：
2009-06-26
影响因子：
4.8
通讯作者：
Inagaki, Fuyuhiko
中科院分区：
文献类型：
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作者：
Takahasi, Kiyohiro;Kumeta, Hiroyuki;Inagaki, Fuyuhiko
RIG-I样受体(RIG-I)包括三个同源基因：RIG-I(维甲酸诱导基因I)、MDA5(黑色素瘤分化相关基因5)和LGP2(遗传学和生理学实验室2)。每个RLR通过识别细胞质中复制的病毒RNA来感知不同的病毒感染。RLR含有一个保守的C末端结构域(CTD)，负责与病毒RNA的结合，包括双链RNA(DsRNA)和5‘-三磷酸单链RNA(5’ppp-ssRNA)。在这里，用核磁共振技术求解了MDA5和LGP2 CTD结构域的溶液结构，并与RIG-I CTD的溶液结构进行了比较。CTD结构域都有相似的折叠和相似的基本表面，但有不同的RNA结合环的结构特征；LGP2和RIG-I CTD结构域有一个很大的基本表面，其中一排由RNA结合环形成。MDA5也有一个大的碱性表面，由于RNA结合环的开放构象，该表面广泛平坦。核磁共振化学位移微扰研究表明，dsRNA和5‘PPP-ssRNA与LGP2 CTD的碱性表面结合，而dsRNA与MDA5 CTD的碱性表面结合，但结合强度较弱，表明RNA结合环的构象与dsRNA和5’PPP-ssRNA的敏感性有关。对碱性表面和RNA结合环的突变研究支持了结构研究的结论。因此，CTD负责与病毒RNA的结合。
The RIG-I like receptor (RLR) comprises three homologues: RIG-I (retinoic acid-inducible gene I), MDA5(melanoma differentiation-associated gene 5), and LGP2 (laboratory of genetics and physiology 2). Each RLR senses different viral infections by recognizing replicating viral RNA in the cytoplasm. The RLR contains a conserved C-terminal domain (CTD), which is responsible for the binding specificity to the viral RNAs, including double-stranded RNA (dsRNA) and 5'-triphosphated single-stranded RNA (5'ppp-ssRNA). Here, the solution structures of the MDA5 and LGP2 CTD domains were solved by NMR and compared with those of RIG-I CTD. The CTD domains each have a similar fold and a similar basic surface but there is the distinct structural feature of a RNA binding loop; The LGP2 and RIG-I CTD domains have a large basic surface, one bank of which is formed by the RNA binding loop. MDA5 also has a large basic surface that is extensively flat due to open conformation of the RNA binding loop. The NMR chemical shift perturbation study showed that dsRNA and 5'ppp-ssRNA are bound to the basic surface of LGP2 CTD, whereas dsRNA is bound to the basic surface of MDA5 CTD but much more weakly, indicating that the conformation of the RNA binding loop is responsible for the sensitivity to dsRNA and 5'ppp-ssRNA. Mutation study of the basic surface and the RNA binding loop supports the conclusion from the structure studies. Thus, the CTD is responsible for the binding affinity to the viral RNAs.