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Estructura de las proteínas. Estructura y actividad de las proteínas TSPO ricas en triptófano

Youzhong Guo¹, Ravi C Kalathur², Qun Liu³

¹Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.

Science (New York, N.Y.)

|January 31, 2015

Resumen

Las proteínas translocadoras (TSPOs) se unen a los esteroides y las porfirinas, actuando como biomarcadores de enfermedades. Este estudio revela sus estructuras cristalinas y actividad catalítica en la degradación de la protoporfirina IX (PpIX), lo que sugiere un papel en la protección contra el estrés oxidativo.

Área de la Ciencia:

La bioquímica es la bioquímica.
Biología Estructural Biología estructural.
Biología Molecular Biología Molecular

Sus antecedentes:

Las proteínas translocadoras (TSPOs) son proteínas conservadas que se unen a los esteroides y las porfirinas.
Los TSPOs están implicados en enfermedades humanas, sirviendo como biomarcadores y objetivos terapéuticos.
Sus secuencias ricas en triptófano están altamente conservadas en todas las especies.

Objetivo del estudio:

Para determinar las estructuras cristalinas de Bacillus cereus TSPO (BcTSPO), incluido su complejo con PK11195.5.
Para investigar la actividad catalítica de BcTSPO en las reacciones de protoporfirina IX (PpIX).
Explorar el papel fisiológico de los TSPOs en la protección contra el estrés oxidativo.

Principales métodos:

Cristalografía de rayos X para obtener estructuras de alta resolución de BcTSPO.
Ensayos bioquímicos para estudiar la degradación de PpIX mediada por BcTSPO.
Mutagénesis dirigida al sitio para investigar los mecanismos de reacción.

Principales resultados:

Las estructuras cristalinas de BcTSPO se determinaron con una resolución de 1,7 Å, revelando un complejo con PK11195.5.
BcTSPO cataliza la degradación de PpIX a un nuevo derivado del hemo.
Los TSPOs de Xenopus y los humanos exhiben actividades similares dirigidas por PpIX.

Conclusiones:

Los datos estructurales y catalíticos desafían la visión tradicional de los TSPOs únicamente como transportistas.
La actividad de degradación de PpIX observada sugiere un papel fisiológico significativo para los TSPOs en la lucha contra el estrés oxidativo.
Investigaciones adicionales sobre la función de TSPO pueden dar lugar a nuevas estrategias terapéuticas para enfermedades que implican estrés oxidativo.

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