Improper folding of proteins has been directly implicated in at least a dozen disease states including Alzheimer's and mad cow disease. Disulfide bonds are important enough for protein folding and stability that simple reduction of these bonds will often cause proteins to unfold. The formation of disulfide bridges is a catalyzed process. We found two catalysts to be involved, DsbA acts as the direct donor of DiSulfide Bonds to newly synthesized periplasmic proteins, DsbB acts to reoxidize DsbA. Our long term goal is to understand how these proteins act to catalyze protein folding. In this project we will seek to answer two basic questions: 1) Why is DsbA so powerful a protein oxidant? and 2) What are the catalytic properties of DsbB that allow it to specifically oxidize DsbA? Two distinct models have been proposed to explain the extreme oxidizing power of Dsba's active site disulfide relative to the related protein, thioredoxin. One model invokes disulfide strain, the other electrostatic interactions that affect the pKa of an active site cysteine. We have designed a multifaceted genetic, biophysical and structural approach that should clearly distinguish between these models. Strain and electrostatic interactions play important roles in the folding and catalytic function of many proteins. Clearly understanding the role of these forces in one model system should thus provide valuable information for understanding their role in other proteins as well. To analyze the redox and catalytic properties of DsbB we propose to use a workbox of tools very similar to those we have successfully used with DsbA. This straightforward characterization should tell us much about the way DsbB functions to reoxidize DsbA and may open the door to investigation of how disulfide bond formation is linked to cellular metabolism. Disulfide bond formation is one of the few covalent modifications that occurs in protein folding. This allows us to phrase our questions in simple biochemical terms. We feel that we now have the potential to understand the function of the DsbA-DsbB disulfide catalytic machine.
| Groitl, Bastian; Horowitz, Scott; Makepeace, Karl A T et al. (2016) Protein unfolding as a switch from self-recognition to high-affinity client binding. Nat Commun 7:10357 |
| Lennon, Christopher W; Thamsen, Maike; Friman, Elias T et al. (2015) Folding Optimization In Vivo Uncovers New Chaperones. J Mol Biol 427:2983-94 |
| Tapley, Timothy L; Körner, Jan L; Barge, Madhuri T et al. (2009) Structural plasticity of an acid-activated chaperone allows promiscuous substrate binding. Proc Natl Acad Sci U S A 106:5557-62 |
| Pan, Jonathan L; Sliskovic, Inga; Bardwell, James C A (2008) Mutants in DsbB that appear to redirect oxidation through the disulfide isomerization pathway. J Mol Biol 377:1433-42 |
| Vertommen, Didier; Depuydt, Matthieu; Pan, Jonathan et al. (2008) The disulphide isomerase DsbC cooperates with the oxidase DsbA in a DsbD-independent manner. Mol Microbiol 67:336-49 |
| Gleiter, Stefan; Bardwell, James C A (2008) Disulfide bond isomerization in prokaryotes. Biochim Biophys Acta 1783:530-4 |
| Hiniker, Annie; Bardwell, James C A (2004) Disulfide relays between and within proteins: the Ero1p structure. Trends Biochem Sci 29:516-9 |
| Kadokura, Hiroshi; Tian, Hongping; Zander, Thomas et al. (2004) Snapshots of DsbA in action: detection of proteins in the process of oxidative folding. Science 303:534-7 |
| Hiniker, Annie; Bardwell, James C A (2004) In vivo substrate specificity of periplasmic disulfide oxidoreductases. J Biol Chem 279:12967-73 |
| Masip, Lluis; Pan, Jonathan L; Haldar, Suranjana et al. (2004) An engineered pathway for the formation of protein disulfide bonds. Science 303:1185-9 |
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