Aminoglycoside Phosphotransferases catalyze the formation of an inhibitor of the SWI/SNF family of DNA‐dependent ATPases

Objective To study the interaction of ADAADi with SWI/SNF proteins. Methods Fluorescence spectroscopy, Circular dichroism and inhibition assay. Results Aminoglycoside phosphotransferases (APHs) utilize ATP as substrate and phosphorylate specific hydroxyl groups in all classes of aminoglycoside antibiotics. This reaction is known to generate phosphoaminoglycoside. In addition to this, a small molecular weight compound labelled as Active DNA‐dependent ATPase A Domain inhibitor (ADAADi) is also generated that is a potent inhibitor of the SWI/SNF family of protein. Here I will be discussing the interaction of ADAADi with Active DNA‐dependent ATPase A Domain (ADAAD), a SWI/SNF protein. Using fluorescence spectroscopy, we show that ADAADi can bind to ADAAD in the absence of ATP and DNA. Binding of ADAADi (I) induces a conformational change in the protein (E) that allows ATP and DNA to bind with greater affinity. However, both the [E.I.ATP] and the [E.I.DNA] complexes are not competent for ATP hydrolysis as the conformation of these ternary complexes is different from the [E.DNA.ATP] complex. Further, we show that ADAADi is an allosteric inhibitor that binds specifically to motif Ia of the protein. Conclusion ADAADi, an allosteric inhibitor, induces a conformational change in the protein that is not conducive for ATP hydrolysis. Source of Research: Council of Scientific and Industrial Research (CSIR).