A calorimetric and structural analysis of cooperativity in the thermal unfolding of the PDZ tandem of human Syntenin-1

• Published in: International journal of biological macromolecules 2023-07, Vol.242 (Pt 1), p.124662-124662, Article 124662
• Main Authors: Martinez, Jose C., Ruiz-Sanz, Javier, Resina, María J., Montero, Fernando, Camara-Artigas, Ana, Luque, Irene
• Format: Article
• Language: English
• Subjects: Calorimetry; Calorimetry, Differential Scanning; Circular Dichroism; Domains in tandem; Folding thermodynamics; Humans; Protein Denaturation; Protein Folding; Protein hydration; Syntenins; Thermodynamics
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2023.124662

Syntenin-1 is a multidomain protein containing a central tandem of two PDZ domains flanked by two unnamed domains. Previous structural and biophysical studies show that the two PDZ domains are functional both isolated and in tandem, occurring a gain in their respective binding affinities when joined through its natural short linker. To get insight into the molecular and energetic reasons of such a gain, here, the first thermodynamic characterization of the conformational equilibrium of Syntenin-1 is presented, with special focus on its PDZ domains. These studies include the thermal unfolding of the whole protein, the PDZ-tandem construct and the two isolated PDZ domains using circular dichroism, differential scanning fluorimetry and differential scanning calorimetry. The isolated PDZ domains show low stability (ΔG 400 kJ·mol−1), and native heat capacity values (above 40 kJ·K−1·mol−1), indicate that these interfacial buried waters play a relevant role in Syntenin-1 folding energetics. [Display omitted] •The linker sequence facilitates the interactions between PDZ domains in the tandem.•Interfacial interactions generate a full cooperative unit between both PDZ domains.•Electrostatic and hydrophobic interactions are present at the tandem interface.•Some water-mediated interactions are energetically relevant at the tandem interface.