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Martinez JC, Ruiz-Sanz J, Resina MJ, Montero F, Camara-Artigas A, Luque I. A calorimetric and structural analysis of cooperativity in the thermal unfolding of the PDZ tandem of human Syntenin-1. Int J Biol Macromol 2023; 242:124662. [PMID: 37119899 DOI: 10.1016/j.ijbiomac.2023.124662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 04/10/2023] [Accepted: 04/24/2023] [Indexed: 05/01/2023]
Abstract
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 < 10 kJ·mol-1) and poor cooperativity compared to the PDZ-tandem, which shows higher stability (20-30 kJ·mol-1) and a fully cooperative behaviour, with energetics similar to that previously described for archetypical PDZ domains. The high-resolution structures suggest that this remarkable increase in cooperativity is associated to strong, water-mediated, interactions at the interface between the PDZ domains, associated to nine conserved hydration regions. The low Tm value (45 °C), the anomalously high unfolding enthalpy (>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.
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Affiliation(s)
- Jose C Martinez
- Department of Physical Chemistry, Institute of Biotechnology and Excellence Unit in Chemistry Applied to Biomedicine and Environment, Faculty of Sciences, University of Granada, Avda. Fuentenueva, s/n, 18071 Granada, Spain.
| | - Javier Ruiz-Sanz
- Department of Physical Chemistry, Institute of Biotechnology and Excellence Unit in Chemistry Applied to Biomedicine and Environment, Faculty of Sciences, University of Granada, Avda. Fuentenueva, s/n, 18071 Granada, Spain.
| | - María J Resina
- Department of Physical Chemistry, Institute of Biotechnology and Excellence Unit in Chemistry Applied to Biomedicine and Environment, Faculty of Sciences, University of Granada, Avda. Fuentenueva, s/n, 18071 Granada, Spain.
| | - Fernando Montero
- Department of Physical Chemistry, Institute of Biotechnology and Excellence Unit in Chemistry Applied to Biomedicine and Environment, Faculty of Sciences, University of Granada, Avda. Fuentenueva, s/n, 18071 Granada, Spain.
| | - Ana Camara-Artigas
- Department of Chemistry and Physics, Agrifood Campus of International Excellence (ceiA3) and CIAMBITAL, University of Almería, Carretera de Sacramento s/n, 04120 Almería, Spain.
| | - Irene Luque
- Department of Physical Chemistry, Institute of Biotechnology and Excellence Unit in Chemistry Applied to Biomedicine and Environment, Faculty of Sciences, University of Granada, Avda. Fuentenueva, s/n, 18071 Granada, Spain.
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Reverse Engineering Analysis of the High-Temperature Reversible Oligomerization and Amyloidogenicity of PSD95-PDZ3. Molecules 2022; 27:molecules27092813. [PMID: 35566161 PMCID: PMC9103278 DOI: 10.3390/molecules27092813] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/09/2022] [Accepted: 04/18/2022] [Indexed: 02/01/2023] Open
Abstract
PSD95-PDZ3, the third PDZ domain of the post-synaptic density-95 protein (MW 11 kDa), undergoes a peculiar three-state thermal denaturation (N ↔ In ↔ D) and is amyloidogenic. PSD95-PDZ3 in the intermediate state (I) is reversibly oligomerized (RO: Reversible oligomerization). We previously reported a point mutation (F340A) that inhibits both ROs and amyloidogenesis and constructed the PDZ3-F340A variant. Here, we “reverse engineered” PDZ3-F340A for inducing high-temperature RO and amyloidogenesis. We produced three variants (R309L, E310L, and N326L), where we individually mutated hydrophilic residues exposed at the surface of the monomeric PDZ3-F340A but buried in the tetrameric crystal structure to a hydrophobic leucine. Differential scanning calorimetry indicated that two of the designed variants (PDZ3-F340A/R309L and E310L) denatured according to the two-state model. On the other hand, PDZ3-F340A/N326L denatured according to a three-state model and produced high-temperature ROs. The secondary structures of PDZ3-F340A/N326L and PDZ3-wt in the RO state were unfolded according to circular dichroism and differential scanning calorimetry. Furthermore, PDZ3-F340A/N326L was amyloidogenic as assessed by Thioflavin T fluorescence. Altogether, these results demonstrate that a single amino acid mutation can trigger the formation of high-temperature RO and concurrent amyloidogenesis.
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