title: The cytolethal distending toxin B sub-unit of Helicobacter hepaticus is a Ca2+- and Mg2+-dependent neutral nuclease.
abstract: The cytolethal distending toxin B (CdtB) of the mouse pathogen Helicobacter hepaticus has cation binding and DNA catalysis residues in common with members of the mammalian deoxyribonuclease I (DNase I) family. The purpose of the present study was to characterize CdtB nuclease. To establish optimal digestion conditions and to evaluate co-factor requirements, a novel and sensitive fluorometric assay that quantitatively determines double stranded DNA digestion was developed. Although the Ca2+- and Mg2+-dependence and neutral properties of CdtB were similar to DNase I, hydrolysis of DNA by CdtB was approximately 100-fold less active than DNase I and was considerably more resistant to inhibition by ZnCl2 and G-actin.
authors.affiliation: Department of Veterinary and Biomedical Sciences, University of Nebraska-Lincoln, Room 147, VBS Building, Lincoln, NE 68583-0905, USA. rohana1@gmail.com
authors.forename: Rohana P
authors.initials: RP
authors.lastname: Dassanayake
authors.forename: Mark A
authors.initials: MA
authors.lastname: Griep
authors.forename: Gerald E
authors.initials: GE
authors.lastname: Duhamel
mesh_terms: D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics / Q000633:toxicity; D002118:Calcium / Q000378:metabolism*; D044923:Helicobacter hepaticus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism*; D009708:Nucleotidases / Q000378:metabolism*
chemical_list: D001427:Bacterial Toxins; C067044:cytolethal distending toxin; D009708:Nucleotidases; C040470:3'-nucleotidase; D008274:Magnesium; D002118:Calcium