Figure 7.

Updated scheme of the cOA signaling pathway. The general scheme of cOA signaling pathway is shown on top, followed by experimentally characterized and predicted components of the pathway classified into five functional categories within gray shapes. Distinct proteins families are shown by oval shapes. CARF families are shown by dark green, and other proteins are shown by oval shapes of different colors, including shades of blue for uncharacterized membrane proteins and shades of gray for protein families without similarity to any characterized proteins. Experimentally characterized ring nucleases are shown by thick yellow outline, and predicted ring nucleases are shown by thick dashed yellow outline in panel A. Components are denoted by general family name if known, CRISPR–Cas ancillary protein names are indicated according to the current nomenclature of cas genes (1). Abbreviations: cOA, cyclic oligoadenylates; CARF, CRISPR-associated Rossmann Fold; WYL, predicted ligand-binding domain associated with many CRISPR–Cas systems (named after the respective amino acids that are partly conserved in the family); HEPN, PIN, RelE, ribonucleases of the respective families; HTH, helix-turn-helix DNA-binding domain; HD, PD-D/ExK, nuclease (or phosphatases) of the respective superfamilies; CorA, divalent cation channel or its homolog.