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Bases estructurales del reconocimiento de sustratos y la especificidad de los nucleótidos en la enzima LanKC de la
Yifan Li1, Kai Shao1, Yicong Li1
1Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117547, Singapore.
ACS chemical biology
|August 29, 2025
Resumen
Determinamos la estructura cryo-EM de SalKC, una enzima clave en la biosíntesis de péptidos antimicrobianos. Una sola diferencia de aminoácidos explica su preferencia por el ATP sobre el GTP, a diferencia de las enzimas relacionadas.
Área de la Ciencia:
- La bioquímica
- Biología estructural
- Microbiología
Sus antecedentes:
- Los lanthipéptidos son péptidos sintetizados por ribosoma y modificados post-traducionalmente (RiPP) con propiedades antimicrobianas significativas.
- La biosíntesis involucra enzimas dedicadas, incluidas las recién identificadas sintetasas trifuncionales de clase III-b LanKC.
Objetivo del estudio:
- Para dilucidar la estructura de la criomicroscopia de alta resolución de SalKC de Streptococcus salivarius.
- Caracterizar bioquímicamente el SalKC y comprender su papel en la maduración del péptido antimicrobiano salivaricina.
- Investigar la base estructural de la selectividad del sustrato y del cofactor en las enzimas LanKC de clase III-b.
Principales métodos:
- Microscopía crioelectrónica de alta resolución (cryo-EM) para la determinación estructural.
- Ensayos bioquímicos para evaluar la actividad enzimática y la preferencia por los cofactores.
- Mutagénesis dirigida al sitio para identificar residuos de aminoácidos clave que influyen en la función enzimática.
Principales resultados:
- La estructura cryo-EM de SalKC reveló una arquitectura dimérica conservada con detalles atómicos del péptido líder unido.
- SalKC demostró una preferencia por el ATP, en contraste con la preferencia GTP de la enzima PneKC relacionada.
- Se identificó una sola sustitución de aminoácidos (Lys303 en SalKC) como el determinante de la especificidad de los nucleótidos, confirmado por estudios de mutación.
Conclusiones:
- El estudio proporciona un marco molecular para comprender los mecanismos conservados y las adaptaciones específicas de las enzimas LanKC de clase III-b.
- Los conocimientos estructurales y bioquímicos aclaran la selectividad del sustrato y del cofactor de SalKC, crucial para la biosíntesis de péptidos antimicrobianos.
- Los hallazgos ponen de relieve la importancia de los residuos de aminoácidos específicos en la función y la especificidad de las enzimas dentro de la familia LanKC.
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