Ubp15p, an ubiquitin hydrolase associated with the peroxisomal export machinery
10.06.2011
Debelyy MO, Platta HW, Saffian D, Hensel A, Thoms S, Meyer HE, Warscheid B, Girzalsky W, Erdmann R.
J Biol Chem. 2011, 286(32):28223-34
The peroxisomal matrix protein import is facilitated by cycling receptors shuttling between the cytosol and the peroxisomal membrane. One crucial step in this cycle is the ATP-dependent release of the receptors from the peroxisomal membrane. This step is facilitated by the peroxisomal AAA-proteins Pex1p and Pex6p with ubiquitination of the receptor being the main signal for its export. Here we report that the AAA-complex contains dislocase as well as deubiquitinating activity. Ubp15p, a ubiquitin hydrolase, was identified as novel constituent of the complex. Ubp15p partially localizes to peroxisomes and is capable to cleave off ubiquitin-moieties from the PTS1-receptor Pex5p. Furthermore, Ubp15p-deficient cells are characterized by a stress-related PTS1- import defect. The results merge to a picture in which removal of ubiquitin of the PTS1-receptor Pex5p is a specific event and might represent a vital step in receptor recycling.
