tailieunhanh - Báo cáo khoa học: Solution and membrane-bound chaperone activity of the diphtheria toxin translocation domain towards the catalytic domain"

During cell intoxication by diphtheria toxin, endosome acidification trig-gers the translocation of the catalytic (C) domain into the cytoplasm. This event is mediated by the translocation (T) domain of the toxin. Previous work suggested that the T domain acts as a chaperone for the C domain during membrane penetration of the toxin. | IFEBS Journal Solution and membrane-bound chaperone activity of the diphtheria toxin translocation domain towards the catalytic domain Anne Chassaing1 Sylvain Pichard1 Anne Araye-Guet1 Julien Barbier1 Vincent Forge2 and Daniel Gillet1 1 Commissariat a I Energie Atomique CEA Institut de Biologie et Technologies de Saclay iBiTecS Service d Ingenierie Moleculaire des Proteines SIMOPRO Gif sur Yvette France 2 Commissariat a l Energie Atomique CEA Institut de Recherche en Technologies et Sciences pour le Vivant IRTSV Laboratoire de Chimie Biologie des Metaux LCBM Grenoble France Keywords diphtheria toxin membrane interaction molten globule protein folding translocation Correspondence D. Gillet Commissariat à l Energie Atomique CEA Institut de Biologie et Technologies de Saclay iBiTecS Service d Ingenierie Moleculaire des Proteines SIMOPRO F-91191 Gif sur Yvette France Fax 33 1 69 08 90 71 Tel 33 1 69 08 76 46 E-mail Received 15 November 2010 revised 20 January 2011 accepted 15 February 2011 doi During cell intoxication by diphtheria toxin endosome acidification triggers the translocation of the catalytic C domain into the cytoplasm. This event is mediated by the translocation T domain of the toxin. Previous work suggested that the T domain acts as a chaperone for the C domain during membrane penetration of the toxin. Using partitioning experiments with lipid vesicles fluorescence spectroscopy and a lipid vesicle leakage assay we characterized the dominant behavior of the T domain over the C domain during the successive steps by which these domains interact with a membrane upon acidification partial unfolding in solution and during membrane binding and then structural rearrangement during penetration into the membrane. To this end we compared for each domain isolated or linked together in a CT protein the toxin lacking the receptor-binding domain each of these steps. The behavior of the T domain is marginally modified