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Conocimientos mecánicos sobre la bifuncional oxigenasa de hierro no hemo carbapenemasa sintetasa por la mutagenesis
Ryan M Phelan1, Craig A Townsend
1Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA.
Journal of the American Chemical Society
|April 25, 2013
Resumen
La carbapenem sintasa (CarC) produce carbapenemas simples a través de la epimerización y desaturación de C5. Esta enzima procesa dos estereoisómeros de sustrato en un antibiótico, lo que sugiere un mecanismo de reacción en dos pasos.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Enzimología Enzimología.
- Biosíntesis de antibióticos para la biosíntesis de antibióticos.
Sus antecedentes:
- Los carbapenems son potentes antibióticos con una actividad de amplio espectro.
- La biosíntesis simple de carbapenem implica una epimerización distinta de C5 y la formación de carboxilato α,β-insaturado en comparación con los carbapenems complejos.
- La carbapenem sintasa (CarC) es una enzima bifuncional crucial para estos pasos terminales.
Objetivo del estudio:
- Para investigar el mecanismo de la carbapenem sintasa (CarC) en la producción de carbapenem simple.
- Para entender cómo CarC procesa sustratos estereoisoméricos en un solo producto antibiótico.
- Para aclarar las funciones de los residuos del sitio activo y los intermedios de reacción en la catálisis de CarC.
Principales métodos:
- Mutagénesis por saturación del sitio activo y los residuos de la segunda esfera de CarC.
- Análisis estructural utilizando cristalografía de rayos X.
- Acoplamiento in silico de sustratos desastereoméricos en el sitio activo de CarC.
Principales resultados:
- CarC exhibe tolerancia diferencial a las mutaciones, proporcionando información sobre su plasticidad estructural.
- El acoplamiento in silico reveló orientaciones de sustrato distintas dentro del sitio activo, que se correlacionan con reacciones específicas (epimerización C5 y desaturación C2 / 3).
- Los hallazgos apoyan un mecanismo catalítico de dos pasos que involucra dos ciclos oxidativos.
Conclusiones:
- La carbapenem sintasa (CarC) emplea un mecanismo único para procesar sustratos estereoisoméricos, produciendo un único antibiótico.
- El esquema de reacción de dos pasos propuesto, que involucra a Tyr67, explica las reacciones de epimerización y desaturación C5 observadas.
- La comprensión del mecanismo de CarC puede informar el desarrollo de nuevos antibióticos carbapenémicos.
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