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Published on: December 28, 2017
Evolution toward small molecule inhibitor resistance affects native enzyme function and stability, generating
Ronan M Kelly1, Hans Leemhuis, Linda Gätjen
1Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Carbohydrate Bioprocessing, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
Developing resistance to small molecule inhibitors like acarbose can significantly impair enzyme function and stability. Evolving cyclodextrin glucanotransferase (CGTase) for acarbose insensitivity revealed substantial costs to catalytic efficiency and thermostability.
Area of Science:
- Biochemistry
- Enzyme Engineering
- Molecular Biology
Background:
- Small molecule inhibitors are crucial for targeting enzymes in human diseases.
- Enzymes can develop resistance to inhibitors through mutations, potentially compromising their native functions.
- Understanding this trade-off is vital for developing effective therapeutics.
Purpose of the Study:
- To investigate the impact of evolving inhibitor resistance on enzyme function and stability.
- To characterize mutations conferring insensitivity to the inhibitor acarbose in cyclodextrin glucanotransferase (CGTase).
Main Methods:
- Utilized error-prone PCR mutagenesis to generate diverse CGTase variants.
- Screened for variants exhibiting reduced sensitivity to the inhibitor acarbose.
- Analyzed mutations' locations, effects on IC50 values, catalytic efficiency, and thermostability.
Main Results:
- Acquired acarbose resistance mutations were concentrated around the CGTase active site, particularly at acceptor substrate binding sites.
- Single mutations (K232E, F283L, A230V) increased acarbose IC50 values 3,500- to 6,700-fold.
- These resistant variants exhibited significantly reduced catalytic efficiency and lower thermostability compared to wild-type CGTase.
Conclusions:
- Enzyme resistance to small molecule inhibitors can be readily acquired.
- Acquiring resistance imposes substantial penalties on native enzyme function, including reduced catalytic efficiency and stability.
- These functional costs limit the evolutionary trajectory of inhibitor-resistant enzyme variants.
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