This is the nucleotidyltransferase domain of DncV from Vibrio cholerae (also known as Cyclic GMP-AMP synthase) and related proteins [1-4]. DncV catalyses the synthesis of 3'3'-cyclic GMP-AMP (3'3'-cGAMP) from GTP and ATP. It is part of the CBASS (cyclic oligonucleotide-based antiphage signaling system) which provides immunity against bacteriophage [1-4]. This protein is required for efficient V.cholerae intestinal colonization and and down-regulates the colonization-influencing process of chemotaxis.

1: Structure-guided reprogramming of human cGAS dinucleotide linkage specificity. Kranzusch PJ, Lee ASY, Wilson SC, Solovykh MS, Vance RE, Berger JM, Doudna JA; Cell. 2014;158:1011-1021. PMID:25131990

2: Structural biochemistry of a Vibrio cholerae dinucleotide cyclase reveals cyclase activity regulation by folates. Zhu D, Wang L, Shang G, Liu X, Zhu J, Lu D, Wang L, Kan B, Zhang JR, Xiang Y; Mol Cell. 2014;55:931-937. PMID:25201413

3: Structural Basis for the Catalytic Mechanism of DncV, Bacterial Homolog of Cyclic GMP-AMP Synthase. Kato K, Ishii R, Hirano S, Ishitani R, Nureki O; Structure. 2015;23:843-850. PMID:25865248

4: Molecular basis of CD-NTase nucleotide selection in CBASS anti-phage defense. Govande AA, Duncan-Lowey B, Eaglesham JB, Whiteley AT, Kranzusch PJ; Cell Rep. 2021;35:109206. PMID:34077735