Oxidative protein folding by an endoplasmic reticulum-localized peroxiredoxin
Ester Zito1, Eduardo Pinho Melo, Yun Yang
1Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY 10016, USA.
Molecular Cell
|December 15, 2010
Summary
Endoplasmic reticulum oxidation 1 (ERO1) is not the only pathway for oxidative protein folding. Researchers discovered that Peroxiredoxin IV (PRDX4) provides an ERO1-independent route for disulfide bond formation in mammalian cells.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Biology
Background:
- Endoplasmic reticulum (ER) oxidation 1 (ERO1) is crucial for oxidative protein folding in simple organisms.
- Mammalian cells show only minor defects in disulfide bond formation when ERO1 is absent, suggesting alternative pathways exist.
Purpose of the Study:
- To identify ERO1-independent pathways responsible for disulfide bond formation in mammalian cells.
- To investigate the role of Peroxiredoxin IV (PRDX4) in oxidative protein folding.
Main Methods:
- Purification of protein disulfide isomerase (PDI) oxidants using a trapping mutant.
- Knockdown of PRDX4 in mouse embryo fibroblasts lacking ERO1.
- Complementation of an ero1 yeast mutation with mammalian PRDX4.
- In vitro experiments with purified PRDX4, PDI, and a hydrogen peroxide-generating system.
Main Results:
- Peroxiredoxin IV (PRDX4) was identified as a key PDI oxidant.
- ERO1-deficient cells were sensitive to PRDX4 knockdown, indicating PRDX4's importance.
- Mammalian PRDX4 rescued the temperature-sensitive phenotype of an ero1 yeast mutation.
- Purified PRDX4 oxidized PDI and reconstituted oxidative folding of RNase A in vitro.
Conclusions:
- ER-localized PRDX4 represents a novel, ERO1-independent pathway for oxidative protein folding in mammalian cells.
- This pathway links hydroperoxide production to disulfide bond formation, complementing the known ERO1-dependent route.
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