Extended Data Fig. 2: Structural analysis of STING-associated CD-NTase enzymes.
From: STING cyclic dinucleotide sensing originated in bacteria
a, Sequence and secondary structure alignment of STING-associated CD-NTases reveals the extent of homology between CdnE homologues from unrelated bacterial strains. Highlighted positions include active-site residues (pink box), and an aspartic acid substitution at a position known to be involved in nucleotide substrate selection (orange box) that is unique to CD-NTases in STING-containing CBASS operons15. A divergent E. coli CdnE that synthesizes cyclic UMP–AMP is included for comparison. b, Crystal structures of FsCdnE and CgCdnE from STING-containing CBASS operons allow direct comparison with previously determined bacterial and human CD-NTase structures. The FsCdnE and CgCdnE structures are most closely related to the clade-E CD-NTase structure from Rhodothermus marinus CdnE (RmCdnE). RmCdnE: PDB 6E0L15; V. cholerae DncV: PDB 4TY057; and human cGAS: PDB 6CTA (DNA omitted for clarity)37.
