Structure of the Human cGAS-DNA Complex Reveals Enhanced Control of Immune Surveillance.

Publication Type:

Journal Article


Cell, Volume 174, Issue 2, p.300-311.e11 (2018)


<p>Cyclic GMP-AMP synthase (cGAS) recognition of cytosolic DNA is critical for immune responses to pathogen replication, cellular stress, and cancer. Existing structures of the mouse cGAS-DNA complex provide a model for enzyme activation but do not explain why human cGAS exhibits severely reduced levels of cyclic GMP-AMP (cGAMP) synthesis compared to other mammals. Here, we discover that enhanced DNA-length specificity restrains human cGAS activation. Using reconstitution of cGAMP signaling in bacteria, we mapped the determinant of human cGAS regulation to two amino acid substitutions in the DNA-binding surface. Human-specific substitutions are necessary and sufficient to direct preferential detection of long DNA. Crystal structures reveal why removal of human substitutions relaxes DNA-length specificity and explain how human-specific&nbsp;DNA interactions favor cGAS oligomerization. These results define how DNA-sensing in humans adapted for enhanced specificity and provide a model of the active human cGAS-DNA complex to enable structure-guided design of cGAS therapeutics.</p>

hcGAS–DNA binary complex and hcGAS–DNA–ATP ternary complex have been deposited in the RCSB Protein Data Bank under accession numbers 6CT9 and 6CTA
6CT9 Ribbon