Electrochemical coupling in the voltage-dependent phosphatase Ci-VSP
Susy C Kohout1, Sarah C Bell, Lijun Liu
1Department of Molecular and Cell Biology, University of California, Berkeley, California, USA.
Nature Chemical Biology
|April 6, 2010
Summary
The voltage-sensing phosphatase Ci-VSP
Area of Science:
- Biochemistry
- Molecular Biology
- Biophysics
Background:
- The voltage-sensing phosphatase (Ci-VSP) comprises a voltage-sensing domain (VSD) and a lipid phosphatase domain (PD).
- The allosteric coupling mechanism between the VSD and PD in Ci-VSP is not fully elucidated.
- Understanding this coupling is crucial for deciphering Ci-VSP's regulatory functions.
Purpose of the Study:
- To investigate the role of the interdomain linker in the allosteric coupling of Ci-VSP.
- To identify the molecular events underlying VSD-PD communication.
- To elucidate the regulatory mechanism of Ci-VSP activity.
Main Methods:
- In vivo functional assays to assess protein coupling.
- Biochemical assays to evaluate enzymatic activity.
- Characterization of voltage-sensing domain motion.
Main Results:
- The interdomain linker is essential for full-length Ci-VSP coupling and isolated PD activity.
- A late-stage VSD motion, dependent on the linker, was identified in the full-length protein.
- This VSD motion requires PI(4,5)P2, the substrate of Ci-VSP.
Conclusions:
- The voltage-driven VSD motion activates Ci-VSP by inducing a linker conformational change, stabilized by PI(4,5)P2.
- Ci-VSP activity is self-limited, as substrate depletion (PI(4,5)P2) decouples the VSD from the enzyme.
- This feedback mechanism ensures precise regulation of cellular lipid levels.
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