The Extraction Mechanism of Monoubiquitinated PEX5 from the Peroxisomal Membrane.
J Mol Biol
; 435(2): 167896, 2023 01 30.
Article
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| MEDLINE
| ID: mdl-36442669
ABSTRACT
The AAA ATPases PEX1â¢PEX6 extract PEX5, the peroxisomal protein shuttling receptor, from the peroxisomal membrane so that a new protein transport cycle can start. Extraction requires ubiquitination of PEX5 at residue 11 and involves a threading mechanism, but how exactly this occurs is unclear. We used a cell-free in vitro system and a variety of engineered PEX5 and ubiquitin molecules to challenge the extraction machinery. We show that PEX5 modified with a single ubiquitin is a substrate for extraction and extend previous findings proposing that neither the N- nor the C-terminus of PEX5 are required for extraction. Chimeric PEX5 molecules possessing a branched polypeptide structure at their C-terminal domains can still be extracted from the peroxisomal membrane thus suggesting that the extraction machinery can thread more than one polypeptide chain simultaneously. Importantly, we found that the PEX5-linked monoubiquitin is unfolded at a pre-extraction stage and, accordingly, an intra-molecularly cross-linked ubiquitin blocked extraction when conjugated to residue 11 of PEX5. Collectively, our data suggest that the PEX5-linked monoubiquitin is the extraction initiator and that the complete ubiquitin-PEX5 conjugate is threaded by PEX1â¢PEX6.
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MEDLINE
Asunto principal:
Peroxisomas
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Ubiquitina
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Receptor de la Señal 1 de Direccionamiento al Peroxisoma
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Proteínas de la Membrana
Idioma:
En
Revista:
J Mol Biol
Año:
2023
Tipo del documento:
Article