CbtA is a family of bacterial and archaeal toxins of type IV toxin-antitoxin system. Toxins from such systems in free-living bacteria inhibit cell growth by targeting essential functions of cellular metabolism. In this case the toxin inhibits cell-division leading to changes in morphology and finally lysis, by interacting with two essential cytoskeletal proteins, FtsZ and MreB. For FtsZ it inhibits its GTPase activity and GTP-dependent polymerization, and for MreB it inhibits its ATP-dependent polymerization. These actions of CbtA appear to occur simultaneously. he cognate antitoxin family is represented by pfam06154.