Stimulator of interferon genes (STING) binds cyclic dinucleotides (CDNs), which induce a large conformational change of the protein. The structural basis of activation of STING by CDNs is rather well understood. Unliganded STING forms an open dimer that undergoes a large conformational change (∼10 Å) to a closed conformation upon the binding of a CDN molecule. This event activates downstream effectors of STING and subsequently leads to activation of the type 1 interferon response. However, a previously solved structure of STING with 3′,3′‐c‐di‐GMP shows Mg atoms mediating the interaction of STING with this CDN. Here, it is shown that no Mg atoms are needed for this interaction; in fact, magnesium can in some cases obstruct the binding of a CDN to STING.

中文翻译：

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干扰素基因的刺激物与环二核苷酸的结合不需要镁。

干扰素基因的刺激物（STING）与环状二核苷酸（CDN）结合，从而诱导蛋白质的构象变化很大。CDN激活STING的结构基础已广为人知。未配体的STING形成一个开放的二聚体，该二聚体在CDN分子结合后会经历一个很大的构象变化（〜10Å），变成一个闭合的构象。此事件激活STING的下游效应子，并随后导致1型干扰素反应的激活。然而，先前用3'，3'-c-di-GMP解决的STING结构显示Mg原子介导STING与该CDN的相互作用。在此，表明该相互作用不需要Mg原子。实际上，镁在某些情况下会阻碍CDN与STING的结合。