The cytolethal distending toxin B sub-unit of Helicobacter hepaticus is a Ca2+- and Mg2+-dependent neutral nuclease

Rohana P. Dassanayake, Mark A. Griep, Gerald E. Duhamel

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)219-225
Number of pages7
JournalFEMS Microbiology Letters
Issue number2
StatePublished - Oct 15 2005


  • Cytolethal distending toxin
  • Helicobacter hepaticus
  • Nuclease
  • Toxin
  • cdtB

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology
  • Genetics


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