A Water-Bridged Cysteine-Cysteine Redox Regulation Mechanism in Bacterial Protein Tyrosine Phosphatases

Resumen

The emergence of multidrug-resistant Mycobacterium tuberculosis (Mtb) strains highlights the need to develop more efficacious and potent drugs. However, this goal is dependent on a comprehensive understanding of Mtb virulence protein effectors at the molecular level. Here, we used a post-expression cysteine (Cys)-to-dehydrolanine (Dha) chemical editing strategy to identify a water-mediated motif that modulates accessibility of the protein tyrosine phosphatase A (PtpA) catalytic pocket. Importantly, this water-mediated Cys-Cys non-covalent motif is also present in the phosphatase SptpA from Staphylococcus aureus, which suggests a potentially preserved structural feature among bacterial tyrosine phosphatases. The identification of this structural water provides insight into the known resistance of Mtb PtpA to the oxidative conditions that prevail within an infected host macrophage. This strategy could be applied to extend the understanding of the dynamics and function(s) of proteins in their native state and ultimately aid in the design of small-molecule modulators. The emergence of Mycobacterium tuberculosis (Mtb) resistance is a serious threat to public health. However, the quest for more efficient drugs against Mtb is hampered by the lack of a detailed understanding of Mtb virulence protein effectors. Here, we describe the swift modification of select Cys residues in multi-Cys proteins directly through chemistry. New insights into the biochemistry of emerging bacterial drug targets were obtained. We reveal a water Cys-Cys bridging mechanism that offers an explanation for the known resistance of Mtb protein tyrosine phosphatase A (PtpA) to the oxidative conditions that prevail within an infected host macrophage. This water Cys-Cys bridge motif is also found in the phosphatase SptpA from Staphylococcus aureus, suggesting its potential conserved structural role. The rationalization of the unique features of PtpA, an important target for Mtb drug discovery, could now be used in the design of novel small-molecule modulators. Using a post-expression chemical editing strategy, Bernardes and colleagues have identified a water-mediated Cys-Cys non-covalent motif in bacterial tyrosine phosphatase A (PtpA) from Mycobacterium tuberculosis (Mtb) and Staphylococcus aureus. Importantly, the identification of the Cys-water-Cys bridge provides insight into the known resistance of Mtb PtpA to the oxidative conditions that prevail within an infected host macrophage. This chemical mutagenesis approach could help the understanding of the dynamics and function(s) of proteins in their native state and ultimately aid in the design of small-molecule modulators. © 2017 The Authors