title: Characterization of putative cholesterol recognition/interaction amino acid consensus-like motif of Campylobacter jejuni cytolethal distending toxin C.
abstract: Cytolethal distending toxin (CDT) produced by Campylobacter jejuni comprises a heterotrimeric complex formed by CdtA, CdtB, and CdtC. Among these toxin subunits, CdtA and CdtC function as essential proteins that mediate toxin binding to cytoplasmic membranes followed by delivery of CdtB into the nucleus. The binding of CdtA/CdtC to the cell surface is mediated by cholesterol, a major component in lipid rafts. Although the putative cholesterol recognition/interaction amino acid consensus (CRAC) domain of CDT has been reported from several bacterial pathogens, the protein regions contributing to CDT binding to cholesterol in C. jejuni remain unclear. Here, we selected a potential CRAC-like region present in the CdtC from C. jejuni for analysis. Molecular modeling showed that the predicted functional domain had the shape of a hydrophobic groove, facilitating cholesterol localization to this domain. Mutation of a tyrosine residue in the CRAC-like region decreased direct binding of CdtC to cholesterol rather than toxin intermolecular interactions and led to impaired CDT intoxication. These results provide a molecular link between C. jejuni CdtC and membrane-lipid rafts through the CRAC-like region, which contributes to toxin recognition and interaction with cholesterol.
authors.affiliation: Department of Microbiology, School of Medicine, Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan. chl@mail.cmu.edu.tw
authors.forename: Chih-Ho
authors.initials: CH
authors.lastname: Lai
authors.forename: Cheng-Kuo
authors.initials: CK
authors.lastname: Lai
authors.forename: Ying-Ju
authors.initials: YJ
authors.lastname: Lin
authors.forename: Chiu-Lien
authors.initials: CL
authors.lastname: Hung
authors.forename: Chia-Han
authors.initials: CH
authors.lastname: Chu
authors.forename: Chun-Lung
authors.initials: CL
authors.lastname: Feng
authors.forename: Chia-Shuo
authors.initials: CS
authors.lastname: Chang
authors.forename: Hong-Lin
authors.initials: HL
authors.lastname: Su
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001427:Bacterial Toxins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D016466:CHO Cells; D016123:Campylobacter jejuni / Q000737:chemistry* / Q000378:metabolism / Q000472:pathogenicity; D002784:Cholesterol / Q000737:chemistry* / Q000378:metabolism; D003412:Cricetulus; D057927:Hydrophobic and Hydrophilic Interactions; D021962:Membrane Microdomains / Q000737:chemistry* / Q000378:metabolism; D062105:Molecular Docking Simulation; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D021122:Protein Subunits / Q000737:chemistry* / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry / Q000235:genetics
chemical_list: D001427:Bacterial Toxins; D021122:Protein Subunits; C067044:cytolethal distending toxin; D014443:Tyrosine; D002784:Cholesterol