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Bivalent-metal binding to CheY protein. Effect on protein conformation
L Kar1, P Matsumura, M E Johnson
1Department of Medicinal Chemistry and Pharmacognosy, University of Illinois, Chicago 60680.
The Biochemical Journal
|October 15, 1992
Summary
Bacterial chemotaxis protein CheY undergoes a conformational change upon binding bivalent metal ions, transitioning between metal-free and metal-bound states. This metal-induced conformational shift, studied using NMR, involves specific residues and clarifies metal ion binding sites.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biophysics
Background:
- CheY is a key protein in bacterial chemotaxis signal transduction.
- Metal ions are essential for CheY's phosphorylation and dephosphorylation.
- Understanding CheY's interaction with metal ions is crucial for elucidating chemotaxis mechanisms.
Purpose of the Study:
- To investigate the interaction of CheY with bivalent metal ions using NMR spectroscopy.
- To identify conformational changes in CheY upon metal ion binding.
- To determine the location of metal ion binding sites on the CheY protein.
Main Methods:
- Paramagnetic relaxation enhancement (PRE) combined with 1D and 2D NMR.
- Nuclear Magnetic Resonance (NMR) spectroscopy techniques including COSY, Hartmann-Hahn, and NOE.
- Comparison of NMR data with existing CheY crystal structures.
Main Results:
- CheY exists in two distinct conformations: metal-free and metal-bound.
- Binding of various bivalent cations (Mg2+, Ca2+, Sr2+, Zn2+, Mn2+) induces a conformational change.
- Specific residues, including Trp-58, Thr-87, and Tyr-106, are significantly affected by metal binding.
- NMR data suggest metal binding occurs near Asp-13 and Asp-57.
Conclusions:
- Bivalent metal ions induce a localized conformational change in CheY.
- The identified binding site is consistent with the cluster of aspartic acid residues.
- Paramagnetic metal-induced relaxation is a valuable tool for studying ligand-binding sites in proteins.