Genetic testing is crucial in inherited arrhythmogenic channelopathies; however, the clinical interpretation of genetic variants remains challenging. Incomplete penetrance, oligogenic, polygenic or multifactorial forms of channelopathies further complicate variant interpretation. We identified the KCNQ1/p.D446E variant in 2/63 patients with long QT syndrome, 30-fold more frequent than in public databases. We thus characterized the biophysical phenotypes of wildtype and mutant IKs co-expressing these alleles with the β-subunit minK in HEK293 cells. KCNQ1 p.446E homozygosity significantly shifted IKs voltage dependence to hyperpolarizing potentials in basal conditions (gain of function) but failed to shift voltage dependence to hyperpolarizing potentials (loss of function) in the presence of 8Br-cAMP, a protein kinase A activator. Basal IKs activation kinetics did not differ among genotypes, but in response to 8Br-cAMP, IKs 446 E/E (homozygous) activation kinetics were slower at the most positive potentials. Protein modeling predicted a slower transition of the 446E Kv7.1 tetrameric channel to the stabilized open state. In conclusion, biophysical and modelling evidence shows that the KCNQ1 p.D446E variant has complex functional consequences including both gain and loss of function, suggesting a contribution to the pathogenesis of arrhythmogenic phenotypes as a functional risk allele.

The research largely focuses on investigating the mechanisms of protein folding and unfolding in proteins, namely triosephosphate isomerase, glucosamine-6-phosphate deaminase, laccase, and bacteriophage M13. The article examines the mechanisms of protein denaturation and renaturation using kinetic equations, thermodynamic models, and molecular dynamics (MD) simulations. These results enhance our understanding of the thermodynamic and kinetic characteristics of these proteins. Furthermore, the study highlights the importance of conserved residues, as well as the influence of environmental conditions such as pH and temperature on protein stability and folding. These discoveries have potential implications in biotechnology and medicine, including the creation of protein-based products and therapies for infectious diseases, and neurodegenerative disorders. The paper acknowledges the groundbreaking contributions of Dr. Andrés Hernández Arana to the field of protein physical chemistry in México. His work has greatly influenced the progress of research in the areas of protein stability and kinetics. Resumen. La investigación se centra en los mecanismos de plegado y desplegado de proteínas; estos mecanismos incluyen la triosafosfato isomerasa, la glucosamina-6-fosfato desaminasa, lacasa y el bacteriófago M13. Se utilizan ecuaciones cinéticas, modelos termodinámicos y simulaciones de dinámica molecular (MD) para analizar los mecanismos de desnaturalización y renaturalización de proteínas. Estos hallazgos nos ayudan a comprender mejor las características cinéticas y termodinámicas de estas proteínas. Además, el estudio destaca la importancia de los residuos conservados y puentes salinos en las proteínas, así como el impacto de los factores ambientales como el pH y la temperatura en la estabilidad y el plegado de las proteínas. Estos hallazgos tienen repercusiones en los campos de la biotecnología y la medicina, como la creación de productos y terapias basados en proteínas para enfermedades infecciosas y trastornos neurodegenerativos. El artículo reconoce el trabajo pionero del Dr. Andrés Hernández Arana en México en el campo de la termodinámica de proteínas. Su trabajo ha sido fundamental para el avance de la investigación en las áreas de cinética y estabilidad de proteínas.