Structure-function analysis of the endoplasmic reticulum oxidoreductase TMX3 reveals interdomain stabilization of the N-terminal redox-active domain
| Autor: | Gerhard Wider, Michael A. Maurer, Lars Ellgaard, Martin Pagac, Johannes Haugstetter, Thomas Blicher |
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| Rok vydání: | 2007 |
| Předmět: |
Protein Folding
Magnetic Resonance Spectroscopy EGF-like domain Protein domain Molecular Sequence Data Molecular Conformation Protein Disulfide-Isomerases Endoplasmic Reticulum Biochemistry Models Biological HAMP domain Structure-Activity Relationship Humans Amino Acid Sequence Protein disulfide-isomerase Molecular Biology Binding Sites Sequence Homology Amino Acid Chemistry Endoplasmic reticulum STIM1 Cell Biology Recombinant Proteins Protein Structure Tertiary Biophysics Protein folding Oxidation-Reduction Binding domain |
| Zdroj: | The Journal of biological chemistry. 282(46) |
| ISSN: | 0021-9258 |
| Popis: | Disulfide bond formation in the endoplasmic reticulum is catalyzed by enzymes of the protein disulfide-isomerase family that harbor one or more thioredoxin-like domains. We recently discovered the transmembrane protein TMX3, a thiol-disulfide oxidoreductase of the protein disulfide-isomerase family. Here, we show that the endoplasmic reticulum-luminal region of TMX3 contains three thioredoxin-like domains, an N-terminal redox-active domain (named a) followed by two enzymatically inactive domains (b and b'). Using the recombinantly expressed TMX3 domain constructs a, ab, and abb', we compared structural stability and enzymatic properties. By structural and biophysical methods, we demonstrate that the reduced a domain has features typical of a globular folded domain that is, however, greatly destabilized upon oxidization. Importantly, interdomain stabilization by the b domain renders the a domain more resistant toward chemical denaturation and proteolysis in both the oxidized and reduced form. In combination with molecular modeling studies of TMX3 abb', the experimental results provide a new understanding of the relationship between the multidomain structure of TMX3 and its function as a redox enzyme. Overall, the data indicate that in addition to their role as substrate and co-factor binding domains, redox-inactive thioredoxin-like domains also function in stabilizing neighboring redox-active domains. |
| Databáze: | OpenAIRE |
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