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El 18-Crown-6-ether utiliza distintas interacciones alostéricas para desacoplar el transporte por la bomba de eflujo
Merissa Brousseau1, Tapasyatanu Dash2, Michael J Rourke3
1Biochemistry Department, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.
Biochemistry
|September 3, 2025
Resumen
La bomba de eflujo multidrug EmrE de Escherichia coli puede ser dirigida para terapias. Descubrimos que el 18-crown-6-ether se une a la lisina 22, induciendo una fuga de protones y ofreciendo nuevos conocimientos sobre la regulación del transportador.
Área de la Ciencia:
- La bioquímica
- Biología molecular
- Microbiología
Sus antecedentes:
- La bomba de eflujo multidrug EmrE de Escherichia coli exhibe múltiples funciones de transporte, lo que presenta un objetivo terapéutico potencial.
- Los sustratos de moléculas pequeñas pueden inducir una susceptibilidad dependiente del transportador, en contraste con el fenotipo típico de resistencia a los antibióticos.
Objetivo del estudio:
- Investigar el sitio de unión y el mecanismo de acción del sustrato de molécula pequeña 18-crown-6-ether en el transportador EmrE.
- Para aclarar el papel de la lisina 22 y la treonina 56 en la regulación alostérica del transporte de EmrE.
Principales métodos:
- Se utilizaron perturbaciones de desplazamiento químico de Resonancia Magnética Nuclear (RMN) para identificar el sitio de unión del éter de 18 coronas.
- Para evaluar la actividad del transportador y los efectos inducidos por el sustrato se utilizaron ensayos de EC50 in vivo y ensayos de fugas liposomales.
Principales resultados:
- Se confirmó que el 18-crown-6-ether se une a la lisina 22 (K22) del transportador de EmrE.
- Se demostró que este sustrato desencadena una fuga de protones no acoplados, lo que indica una interrupción de la regulación normal del transporte.
- El análisis mutacional de K22 solidificó aún más la importancia de este residuo y de T56 en la regulación alosterica.
Conclusiones:
- La lisina 22 es un residuo crítico para la regulación alostérica de EmrE, particularmente en la interacción con la cola C-terminal.
- La comprensión del mecanismo de transporte de EmrE y la regulación por sustratos de susceptibilidad ofrece información aplicable a otras bombas de eflujo multirresistentes.
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