Toxic component of a type I toxin-antitoxin (TA) system. Overexpression causes rapid cell killing and nucleoid condensation of the host cell (PubMed:12123448). Overexpression induces stress-response and a number of membrane protein genes. May inhibit ATP synthesis due to its insertion in the cell inner membrane (By similarity). Expression of the proteinaceous toxin is controlled by an antisense sRNA, in this case RdlD. Only a few of these TA systems have been mechanistically characterized; the mechanisms used to control expression of the toxin gene are not necessarily the same (Probable). Belongs to the Ldr toxic peptide family.