Structural investigation of antidepressant drug and dipalmitoyl phosphatidylcholine interactions by small-angle X-ray scattering method
Dilek Yonar, Elif Hilal Soylu, M. Maral Sünnetçioğlu, Semra İde · Acta Crystallographica Section A Foundations of Crystallography · 2010
Page s138 s138Protein phosphorylation transduces a large set of intracellular signals.One mechanism by which phosphorylation mediates signal transduction is by prompting conformational changes in the target protein or interacting proteins.Previous work described an allosteric site mediating phosphorylationdependent activation of AGC protein kinases.The AGC kinase 3-phosphoinositide-dependent protein kinase 1 (PDK1) is activated by the docking of a phosphorylated motif from substrates.PDK1 is a central component of the growth factor and insulin signaling pathways.PDK1 is responsible for the stimulusdependent phosphorylation and activation of many AGC kinases like Akt/PKB, S6K, RSK and SGK.Thus, our studies on PDK1 are relevant both for the growth factor/cancer field (PDK1 is a validated drug target for cancer treatment) and for insulin/diabetes research.PDK1 is also required for the constitutive phosphorylation of the activation loop of other protein kinases, such as all 12 protein kinase C (PKC) isoforms and the protein kinase C-related protein kinases (PRKs).In all, at least 23 protein kinases are known to be phosphorylated by PDK1.We present the crystal structure [1] of PDK1 bound to a rationally developed low-molecular-weight activator [2] and describe the conformational changes induced by small compounds in the crystal and in solution using a fluorescencebased assay and deuterium exchange experiments.Our results indicate that the binding of the compound produces local changes at the target site, the PIF binding pocket, and also allosteric changes at the ATP binding site and the activation loop.Altogether, we present molecular details of the allosteric changes induced by small compounds that trigger the activation of PDK1 through mimicry of phosphorylationdependent conformational changes.