Architecture and infection-sensing mechanism of the bacterial PARIS defense system.

ABSTRACT: Bacteria and the viruses that infect them (bacteriophages or phages) are engaged in an evolutionary arms race that has resulted in the development of hundreds of bacterial defense systems and myriad phage-encoded counterdefenses^1-5. While the mechanisms of many bacterial defense systems are known¹, how these systems avoid toxicity outside infection yet activate quickly upon sensing phage infection is less well understood. Here, we show that the bacterial Phage Anti-Restriction-Induced System (PARIS) operates as a toxin-antitoxin system, in which the antitoxin AriA sequesters and inactivates the toxin AriB until triggered by the T7 phage counterdefense protein Ocr. Using cryoelectron microscopy (cryoEM), we show that AriA is structurally similar to dimeric SMC-family A

SUBMITTER: Deep A 

PROVIDER: S-EPMC10802264 | biostudies-literature | 2024 Jan

REPOSITORIES: biostudies-literature