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Mecanismo molecular de la biogénesis de clúster de hierro-azufre del ISC revelado por la espectrometría de masas
Cheng-Wei Lin1, Jacob W McCabe1, David H Russell1
1Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States.
Journal of the American Chemical Society
|March 6, 2020
Resumen
Este estudio revela el mecanismo de síntesis de clúster de hierro y azufre utilizando espectrometría de masas nativa. Los hallazgos apoyan un modelo de ensamblaje de clusters de hierro-S, aclarando los procesos biológicos esenciales.
Área de la Ciencia:
- La bioquímica
- Biología molecular
- La biofísica
Sus antecedentes:
- Los grupos de hierro-azufre (Fe-S) son cofactores de proteínas vitales para numerosos procesos biológicos.
- La biogénesis de los clústeres de Fe-S, particularmente a través de la vía ISC que involucra IscS e IscU, es crucial pero no está clara desde el punto de vista mecánico.
- La espectrometría de masas nativa (MS) ofrece una herramienta poderosa para estudiar la estructura, la dinámica y las interacciones de las proteínas en un estado casi nativo.
Objetivo del estudio:
- Para aclarar el mecanismo molecular de la síntesis de clúster de Fe-S.
- Identificar los intermediarios transitorios en la vía de ensamblaje del racimo de Fe-S.
- Investigar las funciones de los iones Zn (II) y Fe (II) en las interacciones IscU e IscS.
Principales métodos:
- Aplicación de la espectrometría de masas nativa (MS) en condiciones anaerobias para estudiar la síntesis de clúster de Fe-S.
- Validación de los resultados de la EM nativa mediante espectroscopia de dicroísmo circular visible.
- Experimentos nativos de EM dependientes del tiempo para capturar intermedios de reacción.
- Investigación de los efectos de la unión de iones Zn{II} y Fe{II} en las interacciones proteicas y la formación de racimos.
Principales resultados:
- La EM nativa capturó con éxito los potenciales intermedios que contienen hierro y azufre durante el ensamblaje de grupos de Fe-S.
- Se demostró que la unión de Zn (II) a IscU estabiliza la proteína, inhibe la biosíntesis de clúster de Fe-S y debilita las interacciones IscU-IscS.
- Se observó que los iones Fe (II) se unen a IscU, promoviendo la transferencia de azufre desde IscS.
Conclusiones:
- Los resultados apoyan un modelo de "hierro primero" para la síntesis de clúster de Fe-S.
- La EM nativa es una técnica poderosa para identificar los intermediarios asociados a las proteínas y aclarar los mecanismos enzimáticos.
- Este trabajo proporciona información mecanicista crítica sobre la biosíntesis de los grupos esenciales de Fe-S.
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