STING環狀二核苷酸感知能力起源於細菌
作者:
小柯機器人發布時間:2020/9/4 14:22:48
美國丹娜法伯癌症研究所Philip J. Kranzusch小組發現,STING環狀二核苷酸感知能力起源於細菌。2020年9月2日,《自然》雜誌在線發表了這項成果。
研究人員發現了在原核生物防禦島內編碼的功能性STING同源物,並揭示了信號激活的保守機制。細菌STING的晶體結構定義了一個最小的同源二聚體支架,其選擇性響應由鄰近cGAS/DncV樣核苷酸轉移酶(CD-NTase)酶合成的c-di-GMP。細菌的STING結構域將環狀二核苷酸識別與蛋白絲形成結合起來,從而驅動TIR效應子結構域寡聚化和NAD+快速剪切。
研究人員重建了STING獲得在後生動物先天免疫力中的進化事件,並確定了來自太平洋牡蠣Crassostrea gigas的全長TIR-STING融合體的結構。比較結構分析表明,向核心STING支架添加後生動物特異性成分如何使從直接效應子功能轉變為抗病毒轉錄的調控。
因此,這些結果解釋了STING依賴性信號傳導的機制,並揭示了原核噬菌體防禦中功能性cGAS-STING途徑的保守性。
據悉,STING(stimulator of interferon genes)是人類細胞中的一種受體,可感知細菌感染過程中釋放的外來環狀二核苷酸以及病毒感染和抗腫瘤免疫中的內源性環狀GMP-AMP信號。STING與其他已知的信號蛋白沒有結構同源性,從而限制了功能分析並無法解釋哺乳動物先天免疫中環狀二核苷酸信號的起源。
附:英文原文
Title: STING cyclic dinucleotide sensing originated in bacteria
Author: Benjamin R. Morehouse, Apurva A. Govande, Adi Millman, Alexander F. A. Keszei, Brianna Lowey, Gal Ofir, Sichen Shao, Rotem Sorek, Philip J. Kranzusch
Issue&Volume: 2020-09-02
Abstract: Stimulator of interferon genes (STING) is a receptor in human cells that senses foreign cyclic dinucleotides released during bacterial infection and endogenous cyclic GMP–AMP signalling during viral infection and antitumour immunity1–5. STING shares no structural homology with other known signalling proteins6–9, limiting functional analysis and preventing explanation of the origin of cyclic dinucleotide signalling in mammalian innate immunity. Here we discover functional STING homologues encoded within prokaryotic defence islands and reveal a conserved mechanism of signal activation. Crystal structures of bacterial STING define a minimal homodimeric scaffold that selectively responds to c-di-GMP synthesized by a neighbouring cGAS/DncV-like nucleotidyltransferase (CD-NTase) enzyme. Bacterial STING domains couple cyclic dinucleotide recognition with protein filament formation to drive TIR effector domain oligomerization and rapid NAD+ cleavage. We reconstruct the evolutionary events following acquisition of STING into metazoan innate immunity and determine the structure of a full-length TIR-STING fusion from the Pacific oyster Crassostrea gigas. Comparative structural analysis demonstrates how metazoan-specific additions to the core STING scaffold enabled a switch from direct effector function to regulation of antiviral transcription. Together, our results explain the mechanism of STING-dependent signalling and reveal conservation of a functional cGAS-STING pathway in prokaryotic bacteriophage defence.
DOI: 10.1038/s41586-020-2719-5
Source: https://www.nature.com/articles/s41586-020-2719-5