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Rpn1 proporciona sitios receptores adyacentes para la unión al sustrato y la deubiquitinación por el proteasoma
Yuan Shi1, Xiang Chen2, Suzanne Elsasser1
1Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
Science (New York, N.Y.)
|February 26, 2016
Resumen
Los investigadores identificaron un sexto receptor de ubiquitina proteasómica, Rpn1, en la levadura. Rpn1 tiene dos sitios de unión que reconocen ubiquitina y dominios similares a la ubiquitina, cruciales para las vías de degradación de proteínas.
Área de la Ciencia:
- Biología celular
- La bioquímica
- Biología molecular
Sus antecedentes:
- La degradación de las proteínas es esencial para la función celular.
- El proteosoma es una máquina celular clave responsable de la degradación de las proteínas.
- El reconocimiento de la ubiquitina es un paso crítico en la orientación de las proteínas para la degradación proteasómica.
Objetivo del estudio:
- Para identificar nuevos receptores de ubiquitina para el proteasoma.
- Para aclarar el mecanismo de reconocimiento de la ubiquitina por el proteosoma.
- Comprender el papel de Rpn1 en la selección y el procesamiento del sustrato.
Principales métodos:
- Genética y bioquímica de la levadura
- Purificación y análisis de proteasomas
- Cristalografía de rayos X de los complejos de Rpn1-ubiquitina
Principales resultados:
- Los cinco receptores de ubiquitina proteasomal conocidos no son esenciales para el reconocimiento de la ubiquitina en la levadura.
- Se identificó y caracterizó un sexto receptor, Rpn1.
- Rpn1 posee dos sitios de unión distintos (T1 y T2) para los dominios de ubiquitina y ubiquitina-como (UBL).
- El sitio T1 se une preferentemente a las cadenas de ubiquitina ligadas a la lisina 48, mediando el reconocimiento del sustrato.
- El sitio T2 se une al dominio UBL de la enzima deubiquitinante Ubp6, lo que facilita el desmontaje de la cadena de ubiquitina.
Conclusiones:
- Rpn1 es un nuevo y esencial receptor de ubiquitina proteasómica en la levadura.
- El mecanismo de reconocimiento de doble sitio de Rpn1 es crítico para la degradación eficiente de las proteínas.
- Rpn1 integra el reconocimiento del sustrato, la interacción del factor de transporte y la deubiquitinación para el procesamiento proteasómico.
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