No magnesium is needed for binding of the stimulator of interferon genes to cyclic dinucleotides

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.
Source: Acta Crystallographica Section F - Category: Biochemistry Authors: Tags: STING cGAS CDN 3 ′ ,3 -c-di-GMP crystal structure research communications Source Type: research