The cytosolic domain of Pex22p stimulates the Pex4p-dependent ubiquitination of the PTS1-receptor

  • Peroxisomal biogenesis is an ubiquitin-dependent process because the receptors required for the import of peroxisomal matrix proteins are controlled via their ubiquitination status. A key step is the monoubiquitination of the import receptor Pex5p by the ubiquitin-conjugating enzyme (E2) Pex4p. This monoubiquitination is supposed to take place after Pex5p has released the cargo into the peroxisomal matrix and primes Pex5p for the extraction from the membrane by the mechano-enzymes Pex1p/Pex6p. These two AAA-type ATPases export Pex5p back to the cytosol for further rounds of matrix protein import. Recently, it has been reported that the soluble Pex4p requires the interaction to its peroxisomal membrane-anchor Pex22p to display full activity. Here we demonstrate that the soluble C-terminal domain of Pex22p harbours its biological activity and that this activity is independent from its function as membrane-anchor of Pex4p. We show that Pex4p can be functionally fused to the trans-membrane segment of the membrane protein Pex3p, which is not directly involved in Pex5p-ubiquitination and matrix protein import. However, this Pex3(N)-Pex4p chimera can only complement the double-deletion strain pex4\(\Delta\)/pex22\(\Delta\) and ensure optimal Pex5p-ubiquitination when the C-terminal part of Pex22p is additionally expressed in the cell. Thus, while the membrane-bound portion Pex22(N)p is not required when Pex4p is fused to Pex3(N)p, the soluble Pex22(C)p is essential for peroxisomal biogenesis and efficient monoubiquitination of the import receptor Pex5p by the E3-ligase Pex12p \(\textit {in vivo}\) and \(\textit {in vitro}\). The results merge into a picture of an ubiquitin-conjugating complex at the peroxisomal membrane consisting of three domains: the ubiquitin-conjugating domain (Pex4p), a membrane-anchor domain (Pex22(N)p) and an enhancing domain (Pex22(C)p), with the membrane-anchor domain being mutually exchangeable, while the Ubc- and enhancer-domains are essential.

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Metadaten
Author:Fouzi El MagraouiGND, Andreas SchrötterGND, Rebecca BrinkmeierGND, Lena KunstGND, Thomas MastalskiGND, Thorsten MüllerORCiDGND, Katrin Marcus-AlicORCiDGND, Helmut E. MeyerGND, Wolfgang GirzalskyGND, Ralf ErdmannORCiDGND, Harald W. PlattaGND
URN:urn:nbn:de:hbz:294-73144
DOI:https://doi.org/10.1371/journal.pone.0105894
Parent Title (English):PLoS ONE
Publisher:Public Library of Science
Place of publication:San Francisco
Document Type:Article
Language:English
Date of Publication (online):2020/07/10
Date of first Publication:2014/08/27
Publishing Institution:Ruhr-Universität Bochum, Universitätsbibliothek
Volume:9
Issue:8, Artikel e105894
First Page:e105894-1
Last Page:e105894-10
Institutes/Facilities:Institut für Biochemie und Pathobiochemie, Abteilung für Systembiochemie
Protein Research Department
open_access (DINI-Set):open_access
Licence (English):License LogoCreative Commons - CC BY 4.0 - Attribution 4.0 International