title: Clostridium difficile toxin A inhibits the kinase activity of extracellular signal-related kinases 1 and 2 through direct binding.
abstract: Clostridium difficile toxin A glucosylates Rho family proteins, resulting in actin filament disaggregation and cell rounding in cultured colonocytes. Given that the cellular toxicity of toxin A is dependent on its receptor binding and subsequent entry into the cell, we herein sought to identify additional colonocyte proteins that might bind to toxin A following its internalization. Our results revealed that toxin A interacted with ERK1 and ERK2 in two human colonocyte cell lines (NCM460 and HT29). A GST-pulldown assay also showed that toxin A can directly bind to ERK1 and ERK2. In NCM460 cells exposed to PMA (an ERK1/2 activator), the phosphorylation of ERK1/2 did not affect the interaction between toxin A and ERK1/2. However, an in vitro kinase assay showed that the direct binding of toxin A to ERK1 or ERK2 inhibited their kinase activities. These results suggest a new molecular mechanism for the cellular toxicity seen in cells exposed to toxin A.
authors.affiliation: Department of Biomedical Science, Jungwon University, Goesan, Chungcheongbukdo 367-805, Korea.
authors.forename: Heon
authors.initials: H
authors.lastname: Seok
authors.forename: Hyo Jung
authors.initials: HJ
authors.lastname: Nam
authors.forename: Seung Taek
authors.initials: ST
authors.lastname: Nam
authors.forename: Jin Ku
authors.initials: JK
authors.lastname: Kang
authors.forename: Sung-Kuk
authors.initials: SK
authors.lastname: Kim
authors.forename: Jong Soo
authors.initials: JS
authors.lastname: Chang
authors.forename: Eun-Mi
authors.initials: EM
authors.lastname: Ha
authors.forename: Young Joo
authors.initials: YJ
authors.lastname: Park
authors.forename: Ho
authors.initials: H
authors.lastname: Kim
mesh_terms: D001427:Bacterial Toxins / Q000378:metabolism*; D002460:Cell Line; D016360:Clostridioides difficile / Q000472:pathogenicity*; D004768:Enterotoxins / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D004847:Epithelial Cells / Q000187:drug effects; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011485:Protein Binding
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins; D004791:Enzyme Inhibitors; C041348:tcdA protein, Clostridium difficile; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3