CBASS (cyclic oligonucleotide-based antiphage signaling system) provides immunity against bacteriophage. The CD-NTase protein synthesizes cyclic nucleotides in response to infection; these serve as specific second messenger signals. The signals activate a diverse range of effectors, leading to bacterial cell death and thus abortive phage infection. A type III-C(AAA) CBASS system (PubMed:32839535). A member of the CBASS system in this bacteria. It does not seem to bind a closure peptide, its exact function is unknown. Interacts with Cap7 (also called HORMA2) and CdnC; forms CdnD:Cap7:Cap8 (also called CdnD:HORMA2:HORMA3) complexes with stoichiometries of 1:1:1 and 2:1:1. Does not seem to be able to assume a closed conformation, does not bind closure peptide. In the Cap7:Cap8 complex only Cap7 binds a closure peptide. Belongs to the bacterial HORMA family. HORMA3 subfamily.