Coordinated Regulation of Accessory Genetic Elements Produces Cyclic Di-Nucleotides for V. cholerae Virulence

Crystal structure of the novel di-nucleotide cyclase from Vibrio cholerae (DncV) responsible for synthesizing a hybrid cyclic GMP-AMP

“…This is supported by the fact that both DncV-produced and synthetic c(3′,5′)GAMP, but not cGAS-generated c[G(2′,5′) pA(3′,5′)p], were entirely blunted in their stimulatory activities in cells expressing a mutant STING (R231A) that only recognizes 2′,5′ linkage-containing cyclic di-nucleotides [7]. The other feature is its capability to produce three different cyclic di-nucleotides, c-di-GMP, c-di-AMP, and the dominant product cGAMP without an activator DNA [2], though recent evidence showed that DncV may not produce c-di-GMP in vivo [8]. To gain a better understanding of the structural differences between these two classes of hybrid di-nucleotide cyclases, i.e., cGAS and DncV, we solved the crystal structure of the full-length DncV (residues V1 to G436) and investigated the catalytic as well as regulatory mechanisms of the NTase superfamily of di-nucleotide cyclases.…”

“…During infection of Vibrio cholerae (V. cholerae), di-nucleotide cyclase Vibrio (DncV) is required for efficient intestinal colonization by V. cholerae and downregulates hyperinfectivity-associated V. cholerae chemotaxis through generation of a regulatory molecule cyclic GMP-AMP (cGAMP) [2].…”

“…Based on previous findings that two conserved acidic residues, D131 and D133, were essential for DncV function [2], we generated a double-mutant protein (dm-DncV) with the two predicted catalytic residues replaced by asparagine residues. The dm-DncV protein showed good properties for crystallization and structure determination.…”

V-cGAPs: attenuators of 3′3′-cGAMP signaling

“…c-di-GMP and c-di-AMP, the first two members of the CDN family, have been implicated in central bacterial processes, and likely act as universal bacterial secondary messengers [1,2]. The latest addition to the bacterial CDN family is 3′3′-cGAMP, a hybrid molecule that is synthesized from ATP and GTP by DncV (a cyclase from V. cholerae) and shown to promote intestinal colonization of V. cholerae by downregulating chemotaxis [3]. Predicted homologs of DncV are present in many other bacterial species [3], indicating that 3′3′-cGAMP may also regulate a wide range of cellular functions, similar to c-di-GMP and c-di-AMP.…”

“…The latest addition to the bacterial CDN family is 3′3′-cGAMP, a hybrid molecule that is synthesized from ATP and GTP by DncV (a cyclase from V. cholerae) and shown to promote intestinal colonization of V. cholerae by downregulating chemotaxis [3]. Predicted homologs of DncV are present in many other bacterial species [3], indicating that 3′3′-cGAMP may also regulate a wide range of cellular functions, similar to c-di-GMP and c-di-AMP. The research on CDNs as second messengers reached new heights following the recent identification of 2′3′-cGAMP, a noncanonical CDN in mammalian cells containing mixed 2′,5′ (at GpA step) and 3′,5′ (at ApG step) linkages, which is synthesized by cGAMP synthase (cGAS) in response to the presence of DNA in the cytosol [4][5][6].…”