Toxic component of a type I toxin-antitoxin (TA) system (By similarity). Part of the plasmid maintenance system, encodes a toxic protein that collapses the transmembrane potential and arrests respiration (By similarity). When the adjacent non-translated flmB (sok) gene is disrupted FlmA no longer functions in plasmid maintenance (i.e. FlmB probably encodes an antisense antitoxin RNA) (By similarity). Translation of FlmA may be coupled to the upstream flmC gene (By similarity). Belongs to the Hok/Gef family.