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HCF-1 se divide en el sitio activo de la O-GlcNAc transferasa

Michael B Lazarus¹, Jiaoyang Jiang, Vaibhav Kapuria

¹Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.

Science (New York, N.Y.)

|December 7, 2013

Resumen

La transferasa N-acetilglucosamina (O-GlcNAc) ligada a O (OGT) divide el factor-1 (HCF-1) de la célula huésped dentro de su sitio activo. Esto revela que la glicosilación de la proteína O-GlcNAc y la escisión del HCF-1 comparten el mismo sitio enzimático.

Área de la Ciencia:

Biología molecular y celular Biología molecular y celular.
La bioquímica es la bioquímica.
Modificaciones después de la traducción.

Sus antecedentes:

El factor de célula huésped-1 (HCF-1) es crucial para regular la progresión del ciclo celular humano.
HCF-1 se somete a una maduración proteolítica que implica la escisión de secuencias repetidas.
La transferasa N-acetilglucosamina (O-GlcNAc) ligada a O (OGT) es una enzima sensible a los nutrientes implicada en este proceso.

Objetivo del estudio:

Para dilucidar el mecanismo molecular por el cual OGT divide HCF-1.
Investigar la base estructural para la interacción entre OGT y HCF-1.
Para determinar si la escisión de HCF-1 y la glicosilación de O-GlcNAc ocurren en el mismo sitio activo.

Principales métodos:

Análisis estructural de la interacción del dominio tetratricopéptido-repetición de la OGT con el HCF-1.
Ensayos bioquímicos para estudiar la escisión de las repeticiones de HCF-1 por OGT.
Mutagénesis dirigida al sitio para alterar los sitios de escisión del HCF-1.

Principales resultados:

El dominio de repetición tetratricopéptido de OGT se une al carboxilo terminal de una repetición HCF-1.
El sitio de escisión del HCF-1 está posicionado dentro del sitio activo de la OGT, cerca de la bolsa de unión uridina difosfato-GlcNAc.
La hendidura se produce entre los residuos de cisteína y glutamato, formando un producto de piroglutamato.
La mutación del glutamato al serina en el sitio de la escisión hace que el HCF-1 repita un sustrato de glicosilación.

Conclusiones:

La escisión proteolítica HCF-1 y la glicosilación de la proteína O-GlcNAc son catalizadas por la OGT dentro del mismo sitio activo.
Este hallazgo proporciona un vínculo mecánico entre la maduración de HCF-1 y la modificación de O-GlcNAc.
El estudio revela una doble función para el sitio activo OGT en el procesamiento de proteínas.

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