RelE toxin can be translated from mRNAs resembling the accumulating cleavage fragments of the relBEF transcript. Cultures of BL21(DE3) contained plasmid pNK31 for T7 expression of an mRNA starting at the 5′end of the full-length (FL) relBEF transcript; pNK32 for expression of an mRNA starting at the position + 28; and pNK33 for expression of an mRNA with disrupted relB open reading frame starting at position +148. Expression of T7 RNA polymerase was induced for 1 h by adding 1mM IPTG. Control cultures were grown without IPTG. Total protein lysates were analyzed for expression of RelE(R81A/R83A)-C-His using western blotting (A), and RNA expression was analyzed by northern hybridization using oligoprobe relE (B).