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Updated: Jun 17, 2026
Gene-targeted Random Mutagenesis to Select Heterochromatin-destabilizing Proteasome Mutants in Fission Yeast
Published on: May 15, 2018
A silent mutation made possible efficient production of active human Frk tyrosine kinase in Escherichia coli
Xiaoyan Yang1, Takayoshi Kinoshita, Masaki Gouda
1Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka, Japan.
Abstract:
Fyn-related kinase (Frk) was first identified using human breast cancer cells. It shares 51% identity with c-Src. Like all members of the Src family, Frk is thought to cause several cancers via dysregulations in signal transduction from cell-surface receptors. The excess activity of Frk on beta-cells has a crucial role in type-I diabetes. A silent mutation at Ile229 conferred a bacterial expression system on the kinase domains of Frk, which allowed for the quick expression and purification of one unphosphorylated and two mono-phosphorylated kinase domains. The C-terminal catalytic segment of the human Frk kinase conjugating hexahistidine purification tag (His-tag) was expressed in Escherichia coli. After first-step purification utilizing the His-tag, an anion-exchange chromatogram yielded three major peaks that had distinguishable phosphorylation characteristics as judged by Western blot analysis and measurement of kinase activity. This result of active protein production should promote drug discovery studies, including highthrough-put screening and structure-based drug design.
Insights
Researchers developed a method to express and purify active Fyn-related kinase (Frk) domains. This advancement aids in studying Frk
Area of Science:
- Biochemistry
- Molecular Biology
- Cancer Research
- Diabetes Research
Background:
- Fyn-related kinase (Frk) is a member of the Src family, implicated in various cancers and type-I diabetes.
- Dysregulation of Frk's signal transduction activity contributes to disease pathogenesis.
- Efficient production of active Frk protein is crucial for detailed study and drug development.
Purpose of the Study:
- To establish a method for the rapid expression and purification of active human Frk kinase domains.
- To enable further drug discovery efforts, including high-throughput screening and structure-based design.
Main Methods:
- A silent mutation (Ile229) was introduced to facilitate bacterial expression of Frk kinase domains.
- The C-terminal catalytic segment of human Frk was expressed in Escherichia coli with a His-tag.
- Protein purification involved His-tag affinity chromatography followed by anion-exchange chromatography.
Main Results:
- Successfully expressed and purified unphosphorylated and mono-phosphorylated forms of Frk kinase domains.
- Three major protein peaks with distinct phosphorylation characteristics were identified.
- Western blot analysis and kinase activity assays confirmed the phosphorylation status and activity of the purified proteins.
Conclusions:
- The developed bacterial expression system allows for efficient production of active Frk kinase domains.
- This facilitates biochemical and structural studies of Frk.
- The availability of active Frk protein is expected to accelerate drug discovery for Frk-related diseases.
