Glucosyltransferase-dependent and -independent effects of TcdB on the proteome of HEp-2 cells.

Toxin B (TcdB) of the nosocomial pathogen C. difficile has been reported to exhibit a glucosyltransferase-dependent and -independent effect on treated HEp-2 cells at toxin concentration above 0.3 nM. In order to investigate and further characterize both effects epithelial cells were treated with wild type TcdB and glucosyltransferase-deficient TcdBNXN and their proteomes were analyzed by LC-MS. Triplex SILAC labeling was used for quantification. Identification of 5212 and quantification of 4712 protein groups was achieved. Out of these 257 were affected by TcdB treatment, 92 by TcdBNXN treatment and 49 by both. TcdB mainly led to changes in proteins that are related to "GTPase mediated signaling" and the "cytoskeleton" while "chromatin" and "cell cycle" related proteins were altered by both, TcdB and TcdBNXN . The obtained dataset of HEp-2 cell proteome helps us to better understand glucosyltransferase-dependent and -independent mechanisms of TcdB and TcdBNXN , particularly those involved in pyknotic cell death. All proteomics data have been deposited in the ProteomeXchange with the dataset identifier PXD006658 (https://proteomecentral.proteomexchange.org/dataset/PXD006658).