title: A thermodynamic study of the third PDZ domain of MAGUK neuronal protein PSD-95 reveals a complex three-state folding behavior.
abstract: The relevance of the C-terminal α helix of the PDZ3 domain of PSD95 in its unfolding process has been explored by achieving the thermodynamic characterization of a construct where the sequence of the nine residues corresponding to such motif has been deleted. Calorimetric traces at neutral pH require the application of a three-state model displaying three different equilibrium processes in which the intermediate state self-associates upon heating, being stable and populated in a wide temperature range. Temperature scans followed by circular dichroism, Fourier transform infrared spectroscopy and dynamic light scattering support the presence of such oligomeric-partially folded species. This study reveals that the deletion of the α3-helix sequence results in a more complex description of the domain unfolding.
authors.affiliation: Departamento de Química Física e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain. Electronic address: jmurciano@ugr.es.
authors.forename: Javier
authors.initials: J
authors.lastname: Murciano-Calles
authors.affiliation: Departamento de Química Física e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain.
authors.forename: Jose C
authors.initials: JC
authors.lastname: Martinez
authors.affiliation: Departament de Bioquímica I Biología Molecular, Facultat de Biociències, Universitat Autónoma de Barcelona, Bellaterra, Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Marin-Argany
authors.affiliation: Departament de Bioquímica I Biología Molecular, Facultat de Biociències, Universitat Autónoma de Barcelona, Bellaterra, Barcelona, Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Villegas
authors.affiliation: Departamento de Química Física e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain. Electronic address: evasan@ugr.es.
authors.forename: Eva S
authors.initials: ES
authors.lastname: Cobos
mesh_terms: D000595:Amino Acid Sequence; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry*; D008958:Models, Molecular; D054731:PDZ Domains; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D013816:Thermodynamics
chemical_list: D047908:Intracellular Signaling Peptides and Proteins
keywords: Differential scanning calorimetry; Oligomeric intermediate; PDZ domain; Protein folding; Thermodynamics; Three-state model