Functional Studies of the Recombinant CdtB, PltA and PltB Subunits from Salmonella enterica serovar Javiana

Cytolethal distending toxin (CDT) is a bacterial toxin that causes HeLa cells to arrest in the G2/M phase of the cell cycle, as well as causing cytoplasmic and nucleus distension of most eukaryotic cells. The CdtB subunit, the active subunit of CDT, is a type I deoxyribonuclease. Here we show that the non-typhoidal Salmonella enterica serovar Javiana encodes CdtB, PltA and PltB in the same pathogenicity islet. Purified His6-tagged CdtB, PltA and PltB subunits were tested for their capacity to induce morphological changes in HeLa cells. S. Javiana CdtB alone was capable of inducing typical signs of cytolethal distension such as cytoplasmic distension and nuclear enlargement. When added individually, purified PltA and PltB do not exhibit toxic activity, whereas the combination of purified His6-tagged CdtB with PltA and PltB elicited morphological changes. Purified His6-tagged CdtB converted supercoiled pUC19 plasmid to relaxed and linear forms, and degrades HeLa cell DNA. These results suggest that the S. Javiana CdtB is likely to play an important role during host infection and disease.