a therapeutic chemical chaperone inhibits cholera intoxication and unfoldingtranslocation of the cholera toxin a1 subunit化学伴侣蛋白抑制治疗霍乱的中毒和unfoldingtranslocation霍乱毒素a1亚基.pdfVIP

A Therapeutic Chemical Chaperone Inhibits Cholera Intoxication and Unfolding/Translocation of the Cholera Toxin A1 Subunit 1. 1. 2 2 1¤a Michael Taylor , Tuhina Banerjee , Fernando Navarro-Garcia , Jazmin Huerta , Shane Massey , 1¤b 1¤c 3 1 Mansfield Burlingame , Abhay H. Pande , Suren A. Tatulian , Ken Teter * 1 Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, United States of America, 2 Department of Cell Biology, ´ ´ Centro de Investigacion y de Estudios Avanzados del IPN (CINVESTAV-Zacatenco), Mexico City, Mexico, 3 Department of Physics, University of Central Florida, Orlando, Florida, United States of America Abstract Cholera toxin (CT) travels as an intact AB5 protein toxin from the cell surface to the endoplasmic reticulum (ER) of an intoxicated cell. In the ER, the catalytic A1 subunit dissociates from the rest of the toxin. Translocation of CTA1 from the ER to the cytosol is then facilitated by the quality control mechanism of ER-associated degradation (ERAD). Thermal instability in the isolated CTA1 subunit generates an unfolded toxin conformation that acts as the trigger for ERAD-mediated translocation to the cytosol. In this work, we show by circular dichroism and fluorescence spectroscopy that exposure to 4- phenylbutyric acid (PBA) inhibited the thermal unfolding of CTA1. This, in turn, blocked the ER-to-cytosol exp