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Una proteasa críptica acopla la deubiquitinación y la degradación por el proteosoma
1Department of Biochemistry, University of Iowa, 51 Newton Road, Iowa City, Iowa 52242, USA.
Nature
|September 28, 2002
Resumen
El proteosoma 26S degrada las proteínas, lo que requiere la eliminación de la ubiquitina. POH1, una subunidad de 19S, actúa como una nueva proteasa dependiente de Zn2+ para la deubiquitinación, crucial para la degradación proteasómica y la viabilidad celular.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- Biología celular Biología celular.
Sus antecedentes:
- El proteosoma 26S es la maquinaria principal para la degradación de proteínas intracelulares en los eucariotas.
- La degradación de las proteínas requiere la eliminación de las cadenas de ubiquitina, un proceso crítico para la translocación del sustrato en el núcleo 20S.
Objetivo del estudio:
- Para aclarar el mecanismo y la importancia de la deubiquitinación durante la degradación proteasomal.
- Para identificar la subunidad específica responsable de la eliminación de la ubiquitina de los sustratos del proteosoma.
Principales métodos:
- Investigó el papel de la subunidad POH1/Rpn11 en la desubiquitinación.
- Evaluó el impacto de la desubiquitinación alterada en las tasas de degradación de proteínas in vitro.
- Examinó la letalidad de los defectos de deubiquitinación en la levadura.
Principales resultados:
- Se identificó POH1 (Rpn11 en levadura) como la subunidad responsable de la deubiquitinación del sustrato dentro del complejo regulador 19S.
- Se demostró que la incapacidad para eliminar la ubiquitina puede limitar la velocidad de degradación proteasomal.
- Se demostró que los defectos en la deubiquitinación son letales en la levadura.
- Caracterizó POH1 como una proteasa dependiente de Zn(2+), distinta de otras enzimas deubiquitinadoras conocidas de la proteasa cisteína (DUB).
Conclusiones:
- POH1 es esencial para la deubiquitinación asociada a la degradación.
- POH1 representa una nueva clase de enzimas deubiquitinadoras de la metaloproteasa.
- La deubiquitinación eficiente por POH1 es vital para la función proteasómica y la supervivencia celular.
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Eukaryotic cells can degrade proteins through several pathways. One of the most important amongst these is the ubiquitin-proteasome pathway. It helps the cell eliminate the misfolded, damaged, or unwarranted cytoplasmic proteins in a highly specific manner.
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It is vital to regulate the activity of enzymatic as well as non-enzymatic proteins inside the cell. This can be achieved either through creating a balance between their rate of synthesis and degradation or regulating the intrinsic activity of the protein. Both these regulation mechanisms play an essential role in the normal functioning of cells.
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