Mitochondrial protein turnover: role of the precursor intermediate peptidase Oct1 in protein stabilization.
Mol Biol Cell
; 22(13): 2135-43, 2011 Jul 01.
Article
en En
| MEDLINE
| ID: mdl-21525245
Most mitochondrial proteins are encoded in the nucleus as precursor proteins and carry N-terminal presequences for import into the organelle. The vast majority of presequences are proteolytically removed by the mitochondrial processing peptidase (MPP) localized in the matrix. A subset of precursors with a characteristic amino acid motif is additionally processed by the mitochondrial intermediate peptidase (MIP) octapeptidyl aminopeptidase 1 (Oct1), which removes an octapeptide from the N-terminus of the precursor intermediate. However, the function of this second cleavage step is elusive. In this paper, we report the identification of a novel Oct1 substrate protein with an unusual cleavage motif. Inspection of the Oct1 substrates revealed that the N-termini of the intermediates typically carry a destabilizing amino acid residue according to the N-end rule of protein degradation, whereas mature proteins carry stabilizing N-terminal residues. We compared the stability of intermediate and mature forms of Oct1 substrate proteins in organello and in vivo and found that Oct1 cleavage increases the half-life of its substrate proteins, most likely by removing destabilizing amino acids at the intermediate's N-terminus. Thus Oct1 converts unstable precursor intermediates generated by MPP into stable mature proteins.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Precursores de Proteínas
/
Metaloendopeptidasas
/
Transportador 1 de Catión Orgánico
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Proteínas Mitocondriales
/
Mitocondrias
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Mol Biol Cell
Asunto de la revista:
BIOLOGIA MOLECULAR
Año:
2011
Tipo del documento:
Article
País de afiliación:
Alemania
Pais de publicación:
Estados Unidos