Corynebacterium diphtheriae putative tellurite-resistance protein (CDCE8392_0813) contributes to the intracellular survival in human epithelial cells and lethality of Caenorhabditis elegans

Corynebacterium diphtheriae, the aetiologic agent of diphtheria,also represents a global medical challenge because of the existence of invasivestrains as causative agents of systemic infections. Although tellurite(TeO3^2-) is toxic to most microorganisms, TeO3^2--resistantbacteria, including C. diphtheriae, exist innature. The presence of TeO3^2--resistance (Te^R)determinants in pathogenic bacteria might provide selective advantages in the naturalenvironment. In the present study, we investigated the role of the putativeTe^R determinant (CDCE8392_813gene) in the virulenceattributes of diphtheria bacilli. The disruption of CDCE8392_0813 gene expression inthe LDCIC-L1 mutant increased susceptibility to TeO3^2- and reactive oxygenspecies (hydrogen peroxide), but not to other antimicrobial agents. The LDCIC-L1mutant also showed a decrease in both the lethality of Caenorhabditis elegansand the survival inside of human epithelial cells compared to wild-typestrain. Conversely, the haemagglutinating activity and adherence to and formation ofbiofilms on different abiotic surfaces were not regulated through the CDCE8392_0813gene. In conclusion, the CDCE8392_813 gene contributes to the Te^R andpathogenic potential of C. diphtheriae.