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Semi-Quantitative Analysis of Peptidoglycan by Liquid Chromatography Mass Spectrometry and Bioinformatics
Published on: October 13, 2020
Formación de enlaces isopéptidos intramoleculares autocatalíticos en bacterias gram-positivas pili: una simulación
Xiangqian Hu1, Hao Hu, Jeffrey A Melvin
1Department of Chemistry, Duke University, Durham, North Carolina 27708, United States of America.
Journal of the American Chemical Society
|December 15, 2010
Resumen
Las bacterias gram-positivas utilizan enlaces isopéptidos de pilina para estabilizar la pili para la adhesión de las células huésped. Este estudio aclara el papel catalítico de los residuos de glutamato en la formación de estos enlaces esenciales, revelando un mecanismo de dos pasos.
Área de la Ciencia:
- Microbiología Microbiología.
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
Sus antecedentes:
- Los patógenos Gram-positivos utilizan pili externo para la adhesión de la célula huésped.
- Los enlaces isopéptidos intramoleculares en las subunidades de pilina estabilizan estas estructuras y ayudan a la polimerización.
- El mecanismo químico preciso de la formación de enlaces isopéptidos en pili sigue siendo poco conocido.
Objetivo del estudio:
- Para investigar el mecanismo molecular de la formación de enlaces isopéptidos intramoleculares en las subunidades pilinas.
- Para aclarar el papel catalítico de los residuos de glutamato en este proceso.
- Para modelar la vía de reacción utilizando métodos computacionales.
Principales métodos:
- Mecánica Cuántica/Mecánica Molecular (QM/MM) cálculos de la trayectoria mínima de energía libre.
- Análisis de las estructuras cristalinas de las pilinas (por ejemplo, Spy0128, RrgB).
- Centrarse en la actividad catalítica de residuos específicos de glutamato.
Principales resultados:
- La formación de enlaces isopéptidos implica un mecanismo de dos pasos iniciado por el ataque nucleofílico de la lisina sobre la asparagina.
- Dos transferencias concertadas de protones ocurren durante la formación de enlaces, liberando amoníaco.
- Los residuos específicos de glutamato (Glu117 y Glu258 en Spy0128) actúan como catalizadores cruciales al facilitar las transferencias de protones.
- Las interacciones dominio-dominio pueden influir en la reactividad de los residuos del sitio activo.
Conclusiones:
- El estudio proporciona un modelo mecanicista detallado para la formación de enlaces isopéptidos en subunidades pilinas.
- Los residuos de glutamato son catalizadores esenciales en este proceso autocatalítico.
- Comprender este mecanismo ofrece información sobre la biogénesis de la pilina en las bacterias gram-positivas.
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