Type II and type VII Toxin-antitoxin systems: an overview and their roles in bacterial biofilm development

Toxin-antitoxin (TA) systems are distinct genetic modules, typically consisting of adjacent toxin and antitoxin genes, and are extensively prevalent in various bacterial species. These genetic elements play key roles in shaping bacterial physiology and pathogenicity, specifically in the regulation of growth dynamics, the mediation of stress responses, and the modulation of bacterial persistence and biofilm formation. TA systems are currently classified into eight types, type II and type VII stand out as pivotal modules for bacterial survival and have drawn much research interest. This review systematically dissects the multifaceted impacts of representative type II and type VII TA systems on the initiation, maturation, and dispersal stages of bacterial biofilm development, while comprehensively unraveling the underlying molecular mechanisms.