title: Cellular interactions of the cytolethal distending toxins from Escherichia coli and Haemophilus ducreyi.
abstract: The cytolethal distending toxins (CDTs) compose a subclass of intracellularly acting genotoxins produced by many Gram-negative pathogenic bacteria that disrupt the normal progression of the eukaryotic cell cycle. Here, the intoxication mechanisms of CDTs from Escherichia coli (Ec-CDT) and Haemophilus ducreyi (Hd-CDT), which share limited amino acid sequence homology, were directly compared. Ec-CDT and Hd-CDT shared comparable in vitro DNase activities of the CdtB subunits, saturable cell surface binding with comparable affinities, and the requirement for an intact Golgi complex to induce cell cycle arrest. In contrast, disruption of endosome acidification blocked Hd-CDT-mediated cell cycle arrest and toxin transport to the endoplasmic reticulum and nucleus, while having no effects on Ec-CDT. Phosphorylation of the histone protein H2AX, as well as nuclear localization, was inhibited for Hd-CdtB, but not Ec-CdtB, in cells expressing dominant negative Rab7 (T22N), suggesting that Hd-CDT, but not Ec-CDT, is trafficked through late endosomal vesicles. In support of this idea, significantly more Hd-CdtB than Ec-CdtB co-localized with Rab9, which is enriched in late endosomal compartments. Competitive binding studies suggested that Ec-CDT and Hd-CDT bind to discrete cell surface determinants. These results suggest that Ec-CDT and Hd-CDT are transported within cells by distinct pathways, possibly mediated by their interaction with different receptors at the cell surface.
authors.affiliation: Department of Microbiology, University of Illinois, Urbana, Illinois 61801.
authors.forename: Amandeep
authors.initials: A
authors.lastname: Gargi
authors.affiliation: Department of Microbiology, University of Illinois, Urbana, Illinois 61801.
authors.forename: Batcha
authors.initials: B
authors.lastname: Tamilselvam
authors.affiliation: Department of Microbiology, University of Illinois, Urbana, Illinois 61801.
authors.forename: Brendan
authors.initials: B
authors.lastname: Powers
authors.affiliation: Department of Microbiology, University of Illinois, Urbana, Illinois 61801.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Prouty
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204.
authors.forename: Tommie
authors.initials: T
authors.lastname: Lincecum
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, California 90095.
authors.forename: Aria
authors.initials: A
authors.lastname: Eshraghi
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, California 90095.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Maldonado-Arocho
authors.affiliation: Department of Microbiology, University of Illinois, Urbana, Illinois 61801; Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801.
authors.forename: Brenda A
authors.initials: BA
authors.lastname: Wilson
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, California 90095.
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Bradley
authors.affiliation: Department of Microbiology, University of Illinois, Urbana, Illinois 61801; Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801. Electronic address: sblanke@illinois.edu.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Blanke
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism*; D019921:Biotinylation; D016466:CHO Cells; D018938:Caco-2 Cells; D002453:Cell Cycle; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D006224:Cricetinae; D003851:Deoxyribonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006191:Haemophilus ducreyi / Q000378:metabolism*; D006367:HeLa Cells; D006657:Histones / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D021381:Protein Transport; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D001427:Bacterial Toxins; C468783:H2AX protein, human; D006657:Histones; D011994:Recombinant Proteins; C067044:cytolethal distending toxin; D003851:Deoxyribonucleases