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

We also observed that catalase not only prevents a decrease of thiol adducts but also prevents an inhibition of enzyme activity. The catalase pretreatment almost completely protected from ATA induced YopH inactivation ( Figure 3A ), as well as CD45 inactivation ( Figure 3B ). The elimination of inhibitory effects of ATA in the presence of catalase and a loss of thiol adducts after ATA treatment may lead to the conclusion that ATA is probably inactivating PTPs due to an oxidative mechanism. Recombinant YopH was pretreated for 15 minutes with 100 nM ATA and subsequently incubated with 10 mM DTT to reverse the ATA inhibition. The increase of activity of YopH was measured every minute on microplate reader as absorbance at 405 nm using pNPP substrate. Data presented as percent of control. B. The amount of modified YopH thiol adducts with NBD (Cys-S-NBD adducts) after 15 minutes of treatment with 100 nM ATA with/without catalase (500U/ml). Data presented as absorbance (420 nm), means ± SD (n = 3). One-way Anova test. * significantly different (P < 0.001). www.impactjournals.com/oncotarget