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 II-A(GA) CBASS system (PubMed:32839535). Catalyzes the synthesis of 3'3'-cyclic GMP-AMP (3'3'-cGAMP) from GTP and ATP, a second messenger in cell signal transduction. Is also able to produce c-di-AMP and c-di-GMP from ATP and GTP. Controls the activity of cGAMP-activated phospholipase CapV, a patatin-like lipase that is a direct 3',3'-cGAMP receptor encoded in the dncV operon. Protects E.coli against phage infection. When capV and dncV are introduced in E.coli MG1655 there is 1000-fold protection against phage P1; protection against other phage (T2, T4, T5, T6 and lambda-vir) requires the 2 subsequent genes (cap2 and cap3). ATP + GTP = 3',3'-cGAMP + 2 diphosphate Binds 1 Mg(2+) ion per subunit. Part of the CBASS operon consisting of capV-dncV-cap2-cap3. The sequence of this protein is available under the NCBI RefSeq accession WP_000558641.1. Belongs to the CD-NTase family. A02 subfamily. Small sacrifice - Issue 239 of September 2021