Biology subjects

Ragucci, A. E.

Publications and source records attributed to Ragucci, A. E..

2 recordsLinked to original sources

bioRxiv2026

Bacterial diadenylate cyclase domains synthesize diverse nucleotide signals in anti-phage defense

Bacterial diadenylate cyclase (DAC) enzymes synthesize the nucleotide signal 3'3' cyclic di-AMP (3'3'-c-di-AMP) to control osmoregulation, cell-wall homeostasis, and DNA-damage responses. Here we discover specialized roles for DAC enzymes in bacterial immunity and define a Panoptes-like system we name Panoptoo as a DAC-containing anti-phage defense that guards against viral immune evasion. The Panoptoo protein PanS is a minimal DAC that constitutively synthesizes 3'3' cyclic UMP-AMP (3'3'-cUA) or 3'3'-c-di-AMP to negatively regulate a partnering PanE S2TM{beta} membrane-targeting effector. We show that Panoptoo decoy signaling acts as a counter-defense to detect phage immune evasion proteins that inhibit nucleotide immune signals. A 1.5 [A] crystal structure of PanS in complex with 3'3'-cUA explains how a symmetry break in the canonical DAC active site enables synthesis of asymmetric signaling molecules. Together, our results uncover a role for DAC domains in bacterial anti-phage defense and expand our understanding of nucleotide signaling in antiviral immunity.

microbiology↗

bioRxiv2025

Nuclease-NTPase systems use shared molecular features to controlbacterial anti-phage defense

Bacteria encode an enormous diversity of defense systems including restriction-modification and CRISPR-Cas that cleave nucleic acid to protect against phage infection. Bioinformatic analyses demonstrate many recently identified anti-phage defense operons are comprised of a predicted nuclease and an accessory NTPase protein, suggesting additional classes of nucleic acid targeting systems remain to be understood. Here we develop large-scale comparative cell biology and biochemical approaches to analyze 16 nuclease-NTPase systems and define shared features that control anti-phage defense. Purification, biochemical characterization, and in vitro reconstitution of nucleic acid targeting for each system demonstrate protein-protein complex formation is a universal feature of nuclease-NTPase systems and explain patterns of phage targeting and susceptibility. We show that some nuclease-NTPase systems use highly degenerate recognition site preferences to enable exceptionally broad nucleic acid degradation. Our results uncover shared principles of anti-phage defense system function and provide a foundation to explain the widespread role of nuclease-NTPase systems in bacterial immunity.

microbiology↗