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Biosíntesis y reactividad de los persulfuros de cisteína en la señalización

Pramod K Yadav¹, Michael Martinov², Victor Vitvitsky¹

¹Department of Biological Chemistry, University of Michigan Medical School , Ann Arbor, Michigan 48109-0600, United States.

Journal of the American Chemical Society

|December 16, 2015

Resumen

El sulfuro de hidrógeno (H2S) es el principal producto de la vía de transsulfuración, no el persulfuro de cisteína (Cys-SSH). Esta vía es crucial para regular las funciones fisiológicas, y el H2S juega un papel clave en la señalización.

Área de la Ciencia:

La bioquímica
Biología celular
Fisiología

Sus antecedentes:

El sulfuro de hidrógeno (H2S) es una molécula de señalización con diversos efectos fisiológicos.
La persulfidación, la modificación de los tiolos de cisteína en persulfidos, es un mecanismo de señalización clave.
El origen de los donantes de persulfuro y su relación con el H2S (producto o precursor) siguen siendo objeto de debate.

Objetivo del estudio:

Investigar las funciones de las enzimas de la vía de transsulfuración en la producción de H2S y persulfuro de cisteína (Cys-SSH).
Determinar si el H2S o el Cys-SSH es el producto primario de la vía de transsulfuración.
Para aclarar la relación entre H2S, Cys-SSH y la persulfidación de proteínas.

Principales métodos:

Análisis cinéticos detallados de las enzimas de la vía de transsulfuración humana (cistioniona beta-sintasa y γ-cistioniasa [CSE]).
Modelado matemático de las concentraciones de sustrato en las células hepáticas.
Experimentos in vitro para evaluar la estabilidad y la reactividad de Cys-SSH.

Principales resultados:

Las enzimas de transsulfuración producen robustamente Cys-SSH, y CSE sintetiza persulfuro de homocisteína.
Las condiciones de reducción citoplasmática favorecen la síntesis de H2S sobre los persulfuros.
El modelado matemático predice H2S como el producto primario, con CSE como el productor dominante.
Cys-SSH es metastable, se descompone en polisulfuros; no se observó un aumento en la persulfidación de proteínas con cistina exógena.

Conclusiones:

H2S, no Cys-SSH, es el producto primario de la vía de transsulfuración en condiciones fisiológicas.
La CSE es la principal enzima responsable de la producción de H2S.
La inestabilidad y descomposición de Cys-SSH en polisulfuros explican la falta de aumento de la persulfidación de proteínas.

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