---

Liao M, et al.  (2006) Endoplasmic reticulum-associated degradation of cytochrome P450 CYP3A4 in Saccharomyces cerevisiae: further characterization of cellular participants and structural determinants. Mol Pharmacol 69(6):1897-904

Abstract: The monotopic, endoplasmic reticulum (ER)-anchored P450s undergo variable proteolytic turnover. CYP3A4, the dominant human liver drug-metabolizing enzyme, is degraded via ubiquitin (Ub)-dependent 26S proteasomal pathway after heterologous expression in S. cerevisiae. This turnover involves the Ub-conjugating enzyme Ubc7p, and the 19S proteasomal subunit Hrd2p, but is independent of Hrd1p/Hrd3p, a major Ub-ligase (E3) involved in ER protein degradation. We now show that CYP3A4 ERAD also involves the Ubc7p-ER anchor Cue1p, as CYP3A4 is significantly stabilized at the stationary growth phase in Cue1p-deficient yeast. To determine whether the other major Ub-ligase Doa10p or Rsp5p involved in ER protein degradation functions in CYP3A4 ERAD, wild type and Doa10p- or Rsp5p-deficient yeast strains were also similarly examined. No appreciable CYP3A4 stabilization was detected in either Doa10p- or Rsp5p-deficient yeast, thereby excluding these E3s and revealing that CYP3A4 ERAD involves a novel or as yet to be identified E3. Similar studies also revealed that the Cdc48p-Ufd1p-Hrd4p complex, responsible for the translocation of polyubiquitinated ER proteins was critical for CYP3A4 ERAD. We previously reported that grafting of the C-terminal (CT) CYP3A4 heptapeptide onto the CYP2B1 C-terminus switched its proteolytic susceptibility from predominantly vacuolar to proteasomal degradation. To determine the relevance of this CT-heptapeptide to CYP3A4 ERAD, CYP3A4 degradation after CT-heptapeptide-deletion (CYP3A4DeltaCT) was similarly examined in yeast. These findings revealed that CYP3A4DeltaCT was also degraded by Ubc7p-26S proteasomal pathway, thereby indicating that this CT-heptapeptide is not critical for CYP3A4 proteasomal degradation. Thus, unlike CYP2B1, CYP3A4 harbors additional/multiple structural degrons for its recruitment into the Ub-proteasomal pathway.

Status: Published

Type: Journal Article

PubMed ID: 16556771

---

Author Searches

To find contact information or other publications by the authors of this paper, follow these three steps:

1. (1) Choose an author,
2. (2) Choose a search parameter,
3. (3) Click to implement

Liao M Faouzi S Karyakin A Correia MA Papers in SGD Colleagues in SGD PubMed Google Scholar

---