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Dimerization by domain hybridization bestows chaperone and isomerase activities
Zhen Zhao1, Yi Peng, Shu-Feng Hao
1National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academi of Sciences, Beijing, China.
The Journal of Biological Chemistry
|August 23, 2003
Summary
Dimerization of monomeric thiol-protein oxidases and reductases, like thioredoxin and protein-disulfide isomerase domains, creates significant isomerase and chaperone activity. This suggests a pathway for proteins to evolve new functions.
Area of Science:
- Biochemistry
- Molecular Biology
- Protein Engineering
Background:
- Monomeric thiol-protein oxidases/reductases, including thioredoxin, DsbA, and protein-disulfide isomerase (PDI) domains, possess limited isomerase and chaperone functions.
- The N-terminal domain of DsbC is known to facilitate protein folding.
Purpose of the Study:
- To investigate if dimerization of these monomeric domains can enhance their biological activities.
- To explore the structural basis for any acquired or enhanced functions in engineered protein hybrids.
Main Methods:
- Construction of four domain hybrids by linking monomeric thioredoxin-fold proteins to the N-terminal domain of DsbC.
- Assessment of isomerase and chaperone activities of the resulting hybrid proteins.
- Three-dimensional structure prediction of the hybrid proteins.
Main Results:
- The four hybrid proteins, DsbCn-Trx, DsbCn-DsbA, DsbCn-PDIa, and DsbCn-PDIb, formed homodimers.
- All hybrids, except DsbCn-PDIb, exhibited significantly enhanced or novel isomerase and chaperone activities.
- Structural predictions indicated a DsbC-like V-shaped conformation with a cleft suitable for binding protein folding intermediates.
Conclusions:
- Dimerization is a key mechanism for generating chaperone and isomerase activity in monomeric thiol-protein oxidases/reductases.
- Protein domain fusion and subsequent dimerization can lead to the evolution of new protein functions and improved biological efficiency.