Recently, we established the detailed mechanisms of nucleic acid-induced activation of OAS1 and cGAS, the individual roles of nucleic acids and substrates, the sources of 2’-specificity of product formation, and the basis of functional divergence between OAS1 and cGAS. We also developed a new method that allows the rational identification of allosteric sites for the specific regulation of enzymes with highly-conserved catalytic centers, and successfully demonstrated its applications. These data and methodology are currently being used to discover and test the potency of allosteric pathways as targets for modulating the activity of cGAS/OAS.

To reveal communication pathways that connect the catalytic centers of innate immune sensors with suitably positioned allosteric pockets, we are dissecting the complete enzymatic cycles of cGAS and OAS1, using approaches that were successfully applied in our previous works on UDP-sugar pyrophosphorylases1,2 and myosin isoforms3,5. The available structural information will be further refined to obtain more detailed information about cGAS dynamics and allostery. Allosteric sites and communication pathways will be tested and validated by the generation of mutant constructs that bias the positioning of active structural elements in a well-defined manner. HPLC/MS-based assays have been established to measure the catalytic activity of wild-type and mutant constructs. Allosteric sites that pass the validation tests are used as targets for the development of small-molecule inhibitors or activators.