Redox process is crucial for inhibitory properties of aurintricarboxylic acid against activity of YopH: virulence factor of Yersinia pestis

Kuban-Jankowska, Alicja; Sahu, Kamlesh K; Niedzialkowski, Pawel; Gorska, Magdalena; Tuszynski, Jack A; Ossowski, Tadeusz; Wozniak, Michal

Due to the fact that YopH, as other PTPs, contains an oxidation-sensitive cysteine located in the active site, we decided to prepare an NBD-Cl assay to calculate the amount of thiol groups after treatment with ATA. We tested the amount of thiol groups modified by NBD-Cl forming Cys-S-NBD adducts. After treatment of recombinant YopH with 100 nM ATA, the quantity of Cys-S-NBD adducts was significantly decreased in comparison with control ( Figure 2B ). Application of ATA has resulted in an over 50% reduction of thiol-NBD adducts compared to control, suggesting that thiol groups in YopH after treatment with ATA are likely to be in oxidized form. Interestingly, the addition of catalase completely prevented ATA induced decrease of thiol adducts ( Figure 2B ).