人および家畜に下痢症を引き起こす新規細菌毒素の構造解析と阻害剤の開発

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The W5052 strain isolated from unusual Tokyo food-poisoning outbreaks did not harbor the cpe nor produce C. perfringens enterotoxin (CPE). On the other hand, they secreted a novel enterotoxin, CPILE. It is consisting of two components: CPILE-a, which acts as an enzymatic ADP-ribosyltransferase and CPILE-b, a membrane binding component.The enterotoxicity of CPILE relies on endocytosis of the CPILE complex into the cytosol. CPILE-b binds to the specific cell receptor and assists translocation of CPILE-a into the target cell. How CPILE-b binds to the particular cell receptor is still unclear.The purified CPILE-b was subjected to cleavage pro-sequence region by trypsin to trigger oligomerization. It should be noted that the SDS-PAGE of the purified CPILE-b showed both pro-sequence and CPILE-b bands. Then, the purified CPILE-b was concentrated and crystalized using standard crystallization kits via hanging drop vapor diffusion method. CPILE-b crystals found after one month screening and SDS-PAGE of selected crystals confirmed that they were CPILE-b crystals. However, poor data set was collected and failed to assign the correct space group even though the good shapes of CPILE-b crystals were used. The pro-sequence probably nicked to CPILE-b and disturbed good quality of crystal formation.In conclusion, N-terminal GST-tag CPILE-b with regular purification procedure failed to separate pro-sequence region from CPILE-b body. The condition that triggers oligomerization of CPILE-b should be further investigation.