title: Changes in signal transducer and activator of transcription 3 (STAT3) dynamics induced by complexation with pharmacological inhibitors of Src homology 2 (SH2) domain dimerization.
abstract: The activity of the transcription factor signal transducer and activator of transcription 3 (STAT3) is dysregulated in a number of hematological and solid malignancies. Development of pharmacological STAT3 Src homology 2 (SH2) domain interaction inhibitors holds great promise for cancer therapy, and a novel class of salicylic acid-based STAT3 dimerization inhibitors that includes orally bioavailable drug candidates has been recently developed. The compounds SF-1-066 and BP-1-102 are predicted to bind to the STAT3 SH2 domain. However, given the highly unstructured and dynamic nature of the SH2 domain, experimental confirmation of this prediction was elusive. We have interrogated the protein-ligand interaction of STAT3 with these small molecule inhibitors by means of time-resolved electrospray ionization hydrogen-deuterium exchange mass spectrometry. Analysis of site-specific evolution of deuterium uptake induced by the complexation of STAT3 with SF-1-066 or BP-1-102 under physiological conditions enabled the mapping of the in silico predicted inhibitor binding site to the STAT3 SH2 domain. The binding of both inhibitors to the SH2 domain resulted in significant local decreases in dynamics, consistent with solvent exclusion at the inhibitor binding site and increased rigidity of the inhibitor-complexed SH2 domain. Interestingly, inhibitor binding induced hot spots of allosteric perturbations outside of the SH2 domain, manifesting mainly as increased deuterium uptake, in regions of STAT3 important for DNA binding and nuclear localization.
authors.affiliation: From the Center for Research in Mass Spectrometry, Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada and.
authors.forename: Diana
authors.initials: D
authors.lastname: Resetca
authors.affiliation: Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada.
authors.forename: Sina
authors.initials: S
authors.lastname: Haftchenary
authors.affiliation: Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada.
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Gunning
authors.affiliation: From the Center for Research in Mass Spectrometry, Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada and dkwilson@yorku.ca.
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Wilson
mesh_terms: D000595:Amino Acid Sequence; D000636:Aminosalicylic Acids / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D041961:Deuterium Exchange Measurement; D051379:Mice; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011485:Protein Binding; D055503:Protein Multimerization / Q000187:drug effects; D050796:STAT3 Transcription Factor / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D054852:Small Molecule Libraries / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D021241:Spectrometry, Mass, Electrospray Ionization; D013449:Sulfonamides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D018909:src Homology Domains
chemical_list: D000636:Aminosalicylic Acids; C000595192:BP-1-102; C000595191:SF-1-066; D050796:STAT3 Transcription Factor; D054852:Small Molecule Libraries; D013449:Sulfonamides
keywords: Allosteric Regulation; Dimerization Inhibitor; Hydrogen Exchange Mass Spectrometry; Hydrogen-Deuterium Exchange; Mass Spectrometry (MS); Protein Dynamic; Signal Transducers and Activators of Transcription 1 (STAT1); Signal Transducers and Activators of Transcription 3