The invention provides mutated, cytotoxic forms of Pseudomonas exotoxin A (PE) comprising a furin cleavage sequence conjugated or fused directly to residues 395-613 of PE or variants of that sequence. These minimal forms of PE are smaller than previous cytotoxic forms of PE, reduce non-specific toxicity, and reduce immunogenicity due to domain II or domain Ib of PE. The invention further provides nucleic acids encoding said PEs, chimeric molecules containing them, and methods of use thereof.
