CARD–NLR–like immunity hub gates gene transfer agent release in Caulobacter crescentus

A CARD–NLR–like system named LypABC in Caulobacter crescentus coordinates GTA particle release by driving host cell lysis, while not being required for DNA packaging; its activity is tightly controlled by the repressor RogA and the regulator CdxB, which also represses GTA activators gafYZ, thereby coupling GTA activation to lysis. Misregulation of LypABC is highly toxic and triggers widespread ghost cell formation, highlighting how bacterial immune modules can be repurposed to promote horizontal gene transfer via GTAs.