title: The 1.8 Å cholix toxin crystal structure in complex with NAD+ and evidence for a new kinetic model.
abstract: Certain Vibrio cholerae strains produce cholix, a potent protein toxin that has diphthamide-specific ADP-ribosyltransferase activity against eukaryotic elongation factor 2. Here we present a 1.8 Å crystal structure of cholix in complex with its natural substrate, nicotinamide adenine dinucleotide (NAD(+)). We also substituted hallmark catalytic residues by site-directed mutagenesis and analyzed both NAD(+) binding and ADP-ribosyltransferase activity using a fluorescence-based assay. These data are the basis for a new kinetic model of cholix toxin activity. Further, the new structural data serve as a reference for continuing inhibitor development for this toxin class.
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Fieldhouse
authors.forename: René
authors.initials: R
authors.lastname: Jørgensen
authors.forename: Miguel R
authors.initials: MR
authors.lastname: Lugo
authors.forename: A Rod
authors.initials: AR
authors.lastname: Merrill
mesh_terms: D020727:ADP-Ribosylation Factors / Q000737:chemistry / Q000378:metabolism; D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D008954:Models, Biological; D008958:Models, Molecular; D009243:NAD / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D014734:Vibrio cholerae / Q000201:enzymology*
chemical_list: D001427:Bacterial Toxins; D009243:NAD; D020727:ADP-Ribosylation Factors; C529269:cholix toxin, Vibrio cholerae