Publicaciones de Francisca Andrea Salas-Sepúlveda
2025
Navarro-Quezada, Nieves; Salas-Sepúlveda, Francisca; Poblete, Horacio; Naranjo, David
Charybdotoxin binding to Shaker K+ channels is temperature sensitive in high external K+ but not in high external Na+ Artículo de revista
En: 2025.
@article{Navarro-Quezada2025,
title = {Charybdotoxin binding to Shaker K+ channels is temperature sensitive in high external K+ but not in high external Na+},
author = {Nieves Navarro-Quezada and Francisca Salas-Sepúlveda and Horacio Poblete and David Naranjo},
doi = {10.1085/jgp.202413590},
year = {2025},
date = {2025-08-07},
urldate = {2025-08-07},
abstract = {Charybdotoxin (CTX), a peptide neurotoxin derived from the scorpion Leiurus quinquestriatus, binds to the external entrance of open voltage-gated K+ channels (VGKCs) with minimal conformational impact. By occluding the VGKC pore, CTX blocks passive K+ flow—a defining function of these membrane proteins. Due to its mechanistic simplicity and high signal-to-noise ratio, the CTX–VGKC interaction is an ideal system to investigate the molecular details of binding and unbinding. CTX bound to the Shaker VGKC exhibits thermal motion (wobbling) that permits access of external K+ to the channel pore. To test whether this wobbling is part of the reaction pathway during toxin–channel interaction, the energetic role of external K+ was examined in the association and dissociation kinetics. A high-affinity Shaker K427E-VGKC variant was expressed in Xenopus oocytes, and its activity was monitored via two-electrode voltage clamp between ∼10 and ∼30°C. Nanomolar applications of CTX to open and closed channels, in the presence of high external Na+ or high K+ concentrations, were used to measure blockade kinetics at different voltages and temperatures. In high K+, both the dissociation and association rates showed higher activation enthalpies, by ∼15 kJ/mol and ∼25 kJ/mol, respectively, compared with high Na+ conditions. However, the association rates under high Na+ and K+ were equal at ∼20°C, indicating a compensatory K+-induced activation entropy. We propose transient CTX-wobbling intermediates in both directions of the reaction pathway. Such a wobbling intermediate could enhance the diversity of productive collisions during association, increasing the efficacy of the scorpion venom.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Charybdotoxin (CTX), a peptide neurotoxin derived from the scorpion Leiurus quinquestriatus, binds to the external entrance of open voltage-gated K+ channels (VGKCs) with minimal conformational impact. By occluding the VGKC pore, CTX blocks passive K+ flow—a defining function of these membrane proteins. Due to its mechanistic simplicity and high signal-to-noise ratio, the CTX–VGKC interaction is an ideal system to investigate the molecular details of binding and unbinding. CTX bound to the Shaker VGKC exhibits thermal motion (wobbling) that permits access of external K+ to the channel pore. To test whether this wobbling is part of the reaction pathway during toxin–channel interaction, the energetic role of external K+ was examined in the association and dissociation kinetics. A high-affinity Shaker K427E-VGKC variant was expressed in Xenopus oocytes, and its activity was monitored via two-electrode voltage clamp between ∼10 and ∼30°C. Nanomolar applications of CTX to open and closed channels, in the presence of high external Na+ or high K+ concentrations, were used to measure blockade kinetics at different voltages and temperatures. In high K+, both the dissociation and association rates showed higher activation enthalpies, by ∼15 kJ/mol and ∼25 kJ/mol, respectively, compared with high Na+ conditions. However, the association rates under high Na+ and K+ were equal at ∼20°C, indicating a compensatory K+-induced activation entropy. We propose transient CTX-wobbling intermediates in both directions of the reaction pathway. Such a wobbling intermediate could enhance the diversity of productive collisions during association, increasing the efficacy of the scorpion venom.
Figueroa, Juan David; Schejtman, Sergio D. Garcia; Tu, Ryan; Muñoz, Marcelo; Salas-Sepúlveda, Francisca; Poblete, Horacio; Langlois, Marc-André; Suuronen, Erik J.; Alarcon, Emilio I.
Ultrashort Peptides as Stabilizing Agents for Colloidal Nanogold Artículo de revista
En: 2025.
@article{Figueroa2025,
title = {Ultrashort Peptides as Stabilizing Agents for Colloidal Nanogold},
author = {Juan David Figueroa and Sergio D. Garcia Schejtman and Ryan Tu and Marcelo Muñoz and Francisca Salas-Sepúlveda and Horacio Poblete and Marc-André Langlois and Erik J. Suuronen and Emilio I. Alarcon},
doi = {10.1021/acsami.4c17794},
year = {2025},
date = {2025-03-25},
urldate = {2025-03-25},
abstract = {Ultrashort peptides hold immense potential as structural tools for enhancing the colloidal stability of nanomaterials, such as nanogold. However, such applications have been largely unexplored in part due to the inherent complexity in designing, synthesizing, and testing short peptides as colloidal nanoparticle stabilizers. In this work, we use a motif-function-guided process for peptide synthesis and high throughput screening to evaluate the colloidal stability of spherical nanogold solutions and pentapeptides. We have successfully built a library of peptides capable of stabilizing colloidal nanogold at peptide concentrations of ≤1.0 μM. This represents a 50–100-fold reduction in the concentration required for stability compared to other small molecules used as capping agents, which illustrates the potential of using short peptide sequences as colloidal nanogold stabilizers. Our findings could significantly impact the future development of high-affinity surface modifiers for the custom engineering of nanogold by providing a deeper understanding of the complex interactions between nanoparticles and peptides.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ultrashort peptides hold immense potential as structural tools for enhancing the colloidal stability of nanomaterials, such as nanogold. However, such applications have been largely unexplored in part due to the inherent complexity in designing, synthesizing, and testing short peptides as colloidal nanoparticle stabilizers. In this work, we use a motif-function-guided process for peptide synthesis and high throughput screening to evaluate the colloidal stability of spherical nanogold solutions and pentapeptides. We have successfully built a library of peptides capable of stabilizing colloidal nanogold at peptide concentrations of ≤1.0 μM. This represents a 50–100-fold reduction in the concentration required for stability compared to other small molecules used as capping agents, which illustrates the potential of using short peptide sequences as colloidal nanogold stabilizers. Our findings could significantly impact the future development of high-affinity surface modifiers for the custom engineering of nanogold by providing a deeper understanding of the complex interactions between nanoparticles and peptides.
Galaz-Araya, Constanza; Zúñiga-Núñez, Daniel; Salas-Sepúlveda, Francisca; Herrera-Morande, Alejandra; Aspée, Alexis; Poblete, Horacio; Zamora, Ricardo A.
En: 2025.
@article{Galaz-Araya2025b,
title = {Theoretical evaluation of a bulky ortho-thioalkyl-azobenzene as an alternative to photocontrol structural cytotoxic effects of metal-free and disulfide oxidized hSOD1 in pathogenesis of ALS},
author = {Constanza Galaz-Araya and Daniel Zúñiga-Núñez and Francisca Salas-Sepúlveda and Alejandra Herrera-Morande and Alexis Aspée and Horacio Poblete and Ricardo A. Zamora },
doi = {10.1039/D4RA08972C},
year = {2025},
date = {2025-03-24},
urldate = {2025-03-24},
abstract = {This study presents a novel photopharmacological strategy to mitigate the cytotoxic effects of apo-hSOD1S–S, a misfolded protein implicated in neurodegenerative diseases. Using quantum chemical calculations and molecular dynamics simulations, we demonstrate that ortho-thio-substituted azobenzene photoswitches (ortho-TABPs) can be employed to precisely modulate the dynamics of the crucial electrostatic loop (EL) in apo-hSOD1S–S. We establish that larger ortho-S-alkyl substituents on the ortho-TABP enhance its redox stability, favouring the cis conformation through the modulation of the position of the n → π* transition. This stability is crucial for operation within the reducing cellular environment. Furthermore, we demonstrate the successful and consistent photomodulation of EL conformational dynamics in apo-hSOD1S–S through covalent tethering of an ortho-TABP. This control is achieved by leveraging the thermodynamically stable trans conformation of the photoswitch, which allosterically influences the EL and consequently, the geometry of the Zn-binding site, a critical determinant of apo-hSOD1S–S cytotoxicity. This work paves the way for developing targeted therapies for neurodegenerative diseases by demonstrating the precise and effective photomodulation of apo-hSOD1S–S via rationally designed ortho-TABPs.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This study presents a novel photopharmacological strategy to mitigate the cytotoxic effects of apo-hSOD1S–S, a misfolded protein implicated in neurodegenerative diseases. Using quantum chemical calculations and molecular dynamics simulations, we demonstrate that ortho-thio-substituted azobenzene photoswitches (ortho-TABPs) can be employed to precisely modulate the dynamics of the crucial electrostatic loop (EL) in apo-hSOD1S–S. We establish that larger ortho-S-alkyl substituents on the ortho-TABP enhance its redox stability, favouring the cis conformation through the modulation of the position of the n → π* transition. This stability is crucial for operation within the reducing cellular environment. Furthermore, we demonstrate the successful and consistent photomodulation of EL conformational dynamics in apo-hSOD1S–S through covalent tethering of an ortho-TABP. This control is achieved by leveraging the thermodynamically stable trans conformation of the photoswitch, which allosterically influences the EL and consequently, the geometry of the Zn-binding site, a critical determinant of apo-hSOD1S–S cytotoxicity. This work paves the way for developing targeted therapies for neurodegenerative diseases by demonstrating the precise and effective photomodulation of apo-hSOD1S–S via rationally designed ortho-TABPs.
2022
Rosales-Rojas, Roberto; Zuñiga-Bustos, Matías; Salas-Sepúlveda, Francisca; Galaz-Araya, Constanza; Zamora, Ricardo A.; Poblete, Horacio
Self-Organization Dynamics of Collagen-like Peptides Crosslinking Is Driven by Rose-Bengal-Mediated Electrostatic Bridges Artículo de revista
En: Pharmaceutics, vol. 14, no 6, pp. 1148, 2022, ISSN: 1999-4923.
@article{rosales-rojas_self-organization_2022,
title = {Self-Organization Dynamics of Collagen-like Peptides Crosslinking Is Driven by Rose-Bengal-Mediated Electrostatic Bridges},
author = {Roberto Rosales-Rojas and Matías Zuñiga-Bustos and Francisca Salas-Sepúlveda and Constanza Galaz-Araya and Ricardo A. Zamora and Horacio Poblete},
url = {https://www.mdpi.com/1999-4923/14/6/1148},
doi = {10.3390/pharmaceutics14061148},
issn = {1999-4923},
year = {2022},
date = {2022-05-01},
urldate = {2025-01-02},
journal = {Pharmaceutics},
volume = {14},
number = {6},
pages = {1148},
abstract = {The present work focuses on the computational study of the structural micro-organization of hydrogels based on collagen-like peptides (CLPs) in complex with Rose Bengal (RB). In previous studies, these hydrogels computationally and experimentally demonstrated that when RB was activated by green light, it could generate forms of stable crosslinked structures capable of regenerating biological tissues such as the skin and cornea. Here, we focus on the structural and atomic interactions of two collagen-like peptides (collagen-like peptide I (CLPI), and collagen-like peptide II, (CLPII)) in the presence and absence of RB, highlighting the acquired three-dimensional organization and going deep into the stabilization effect caused by the dye. Our results suggest that the dye could generate a ternary ground-state complex between collagen-like peptide fibers, specifically with positively charged amino acids (Lys in CLPI and Arg in CLPII), thus stabilizing ordered three-dimensional structures. The discoveries generated in this study provide the structural and atomic bases for the subsequent rational development of new synthetic peptides with improved characteristics for applications in the regeneration of biological tissues during photochemical tissue bonding therapies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The present work focuses on the computational study of the structural micro-organization of hydrogels based on collagen-like peptides (CLPs) in complex with Rose Bengal (RB). In previous studies, these hydrogels computationally and experimentally demonstrated that when RB was activated by green light, it could generate forms of stable crosslinked structures capable of regenerating biological tissues such as the skin and cornea. Here, we focus on the structural and atomic interactions of two collagen-like peptides (collagen-like peptide I (CLPI), and collagen-like peptide II, (CLPII)) in the presence and absence of RB, highlighting the acquired three-dimensional organization and going deep into the stabilization effect caused by the dye. Our results suggest that the dye could generate a ternary ground-state complex between collagen-like peptide fibers, specifically with positively charged amino acids (Lys in CLPI and Arg in CLPII), thus stabilizing ordered three-dimensional structures. The discoveries generated in this study provide the structural and atomic bases for the subsequent rational development of new synthetic peptides with improved characteristics for applications in the regeneration of biological tissues during photochemical tissue bonding therapies.
