ABSTRACT
The molecular chaperone TRAP1 is the mitochondrial paralog of Hsp90 and is overexpressed in many cancer cells. The orthosteric ATP-binding site of TRAP1 has been considered the primary inhibitor binding location, but TRAP1 allosteric modulators have not yet been investigated. Here, we generated and characterized the Hsp90 inhibitor PU-H71, conjugated to the mitochondrial delivery vehicle triphenylphosphonium (TPP) with a C10 carbon spacer, named SMTIN-C10, to enable dual binding to orthosteric and allosteric sites. In addition to tight binding with the ATP-binding site through the PU-H71 moiety, SMTIN-C10 interacts with the E115 residue in the N-terminal domain through the TPP moiety and subsequently induces structural transition of TRAP1 to a tightly packed closed form. The data indicate the existence of a druggable allosteric site neighboring the orthosteric ATP pocket that can be exploited to develop potent TRAP1 modulators.
Subject(s)
Allosteric Site/drug effects , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Benzodioxoles/chemistry , Benzodioxoles/pharmacology , HSP90 Heat-Shock Proteins/antagonists & inhibitors , Purines/chemistry , Purines/pharmacology , Cell Line, Tumor , HSP90 Heat-Shock Proteins/chemistry , HSP90 Heat-Shock Proteins/metabolism , Humans , Molecular Docking Simulation , Neoplasms/drug therapy , Neoplasms/metabolism , Protein Conformation/drug effectsABSTRACT
Mitochondria targeting sensitizers are continuing to gain importance in photodynamic therapy (PDT). Members of the 90 kDa heat shock protein (Hsp90) family, including TRAP1 (Hsp75), are overexpressed in cancer cells and help to control the antiapoptotic protein activity. The present work introduces an Hsp90 inhibitor-mitochondria targeting indocyanine dye conjugate (IR-PU) for high PDT efficacy.