OBJECTIVETo study lysosomes involvement in the degradation of ricin A chain.

METHODSA lysosome-targeted singal KFERQ was added to the C terminus of rRTA by DNA recombinant technology. A pKK223.3 expression system in E. coli was used to produce recombinant ricine A chain (rRTA) and rRTA-KFERQ. Recombinant proteins were purified by affinity chromatography using Blue-Sepharose 6B. The cytotoxicity of recombinant proteins was measured by the MTT method.

RESULTSRecombinant RTA-KFERQ was 49.87%, 54.18% and 88.68% less cytotoxic than RTA itself on the three cell lines HEPG2, Hela and A549, respectively.

CONCLUSIONLysosomes can degrade, but not completely inactivate RTA in different cells, suggesting cells may have other degradation pathways for RTA.