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Updated: May 1, 2026
Profiling of Methyltransferases and Other S-adenosyl-L-homocysteine-binding Proteins by Capture Compound Mass Spectrometry CCMS
Published on: December 20, 2010
Designing a whole-cell biosensor applicable for S-adenosyl-l-methionine-dependent methyltransferases
Zhen Zhen1, La Xiang2, Shizhong Li1
1Department of Microbial Physiological & Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China; University of Chinese Academy of Sciences, 100049, Beijing, China.
A novel whole-cell biosensor was developed to improve methyl-group transfer efficiency. Directed evolution enhanced caffeic acid 3-O-methyltransferase activity, significantly boosting ferulic acid biosynthesis for natural product production.
Area of Science:
- Biotechnology and Synthetic Biology
- Enzyme Engineering
- Metabolic Engineering
Background:
- Methyl-group transfer is crucial for biosynthesis but often limited by enzyme efficiency and methyl donor availability.
- Developing efficient screening strategies is key to improving enzymes involved in methyl-group transfer.
- O-methyltransferases (OMTs) play vital roles in natural product biosynthesis, but their efficiency can be a bottleneck.
Purpose of the Study:
- To create a high-throughput screening method for enhancing methyl-group transfer.
- To engineer caffeic acid 3-O-methyltransferase (AtComT) for improved activity and product yield.
- To validate the utility of a novel l-homocysteine biosensor for assessing methyl transfer efficiency.
Main Methods:
- Development of an l-homocysteine whole-cell biosensor based on Escherichia coli MetR.
- Application of directed evolution to Arabidopsis thaliana caffeic acid 3-O-methyltransferase (AtComT) using the biosensor.
- Characterization of evolved mutants, including analysis of protein dimerization and catalytic efficiency.
- Ferulic acid biosynthesis assay using tyrosine as a substrate with the evolved AtComT.
Main Results:
- The l-homocysteine biosensor successfully reported intracellular accumulation of l-homocysteine, reflecting methyl transfer activity.
- Directed evolution yielded an AtComT mutant with a 13.8-fold improvement in converting caffeic acid to ferulic acid.
- The best mutant showed a 5.4-fold increase in catalytic efficiency, attributed to improved OMT dimerization.
- The evolved AtComT mutant achieved high-yield ferulic acid biosynthesis (3448 mg L⁻¹) with 88.8% conversion rate.
Conclusions:
- The developed l-homocysteine biosensor is a valuable tool for high-throughput screening of methyl transfer processes.
- Enzyme engineering via directed evolution can significantly enhance OMT activity and product biosynthesis.
- Improved protein dimerization is a key factor in boosting OMT catalytic efficiency.
- This approach holds promise for the efficient biosynthesis of diverse natural products.
