Viral RNA recognition by LGP2 and MDA5, and activation of signaling through step-by-step conformational changes.
Viral RNA recognition by LGP2 and MDA5, and activation of signaling through step-by-step conformational changes.
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DOI：
10.1093/nar/gkaa935
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发表时间：
2020-11-18
影响因子：
14.9
通讯作者：
Fujita T
中科院分区：
文献类型：
--
作者：
Duic I;Tadakuma H;Harada Y;Yamaue R;Deguchi K;Suzuki Y;Yoshimura SH;Kato H;Takeyasu K;Fujita T
哺乳动物细胞中的细胞质RIG-I样受体（RLR）蛋白识别病毒RNA并启动导致IFN-β诱导的抗病毒应答。黑色素瘤分化相关蛋白5（MDA 5）形成纤维沿着病毒dsRNA和传播的抗病毒反应，通过一个信号结构域，串联CARD。最神秘的RLR，遗传学和生理学实验室（LGP 2），缺乏信号传导结构域，但通过与MDA 5合作在病毒传感中发挥作用。然而，目前还不清楚LGP 2如何协调纤维形成和随后的MDA 5激活。我们利用生物化学和生物物理学的方法来观察纤维的形成和MDA 5的构象。LGP 2促进了MDA 5纤维的组装。LGP 2以32 nm的平均分子间距离掺入纤维中，表明与MDA 5形成杂寡聚体。此外，有限的蛋白酶消化揭示了LGP 2诱导MDA 5上的显著构象变化，促进其CARD的暴露。虽然ATP水解能有效地解离纤维，但MDA 5仍保持其活性构象参与下游信号传导。我们的研究证明了LGP 2和MDA 5的协调作用，其中LGP 2作为MDA 5成核剂和必需的合作伙伴在MDA 5转化为活性构象。我们揭示了LGP 2介导的调节MDA 5抗病毒先天免疫应答的机制基础。
Cytoplasmic RIG-I-like receptor (RLR) proteins in mammalian cells recognize viral RNA and initiate an antiviral response that results in IFN-β induction. Melanoma differentiation-associated protein 5 (MDA5) forms fibers along viral dsRNA and propagates an antiviral response via a signaling domain, the tandem CARD. The most enigmatic RLR, laboratory of genetics and physiology (LGP2), lacks the signaling domain but functions in viral sensing through cooperation with MDA5. However, it remains unclear how LGP2 coordinates fiber formation and subsequent MDA5 activation. We utilized biochemical and biophysical approaches to observe fiber formation and the conformation of MDA5. LGP2 facilitated MDA5 fiber assembly. LGP2 was incorporated into the fibers with an average inter-molecular distance of 32 nm, suggesting the formation of hetero-oligomers with MDA5. Furthermore, limited protease digestion revealed that LGP2 induces significant conformational changes on MDA5, promoting exposure of its CARDs. Although the fibers were efficiently dissociated by ATP hydrolysis, MDA5 maintained its active conformation to participate in downstream signaling. Our study demonstrated the coordinated actions of LGP2 and MDA5, where LGP2 acts as an MDA5 nucleator and requisite partner in the conversion of MDA5 to an active conformation. We revealed a mechanistic basis for LGP2-mediated regulation of MDA5 antiviral innate immune responses.
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影响因子：
14.9
作者：
Pippig DA;Hellmuth JC;Cui S;Kirchhofer A;Lammens K;Lammens A;Schmidt A;Rothenfusser S;Hopfner KP
通讯作者：
Hopfner KP
影响因子：
3.7
作者：
Childs KS;Randall RE;Goodbourn S
通讯作者：
Goodbourn S
影响因子：
4.8
作者：
Takahasi, Kiyohiro;Kumeta, Hiroyuki;Inagaki, Fuyuhiko
通讯作者：
Inagaki, Fuyuhiko
影响因子：
5.4
作者：
Komuro, Akihiko;Horvath, Curt M.
通讯作者：
Horvath, Curt M.
影响因子：
4.8
作者：
Bamming, Darja;Horvath, Curt M.
通讯作者：
Horvath, Curt M.