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Three-dimensional solution structure of a unique S100 protein.
Vaithiyalingam Sivaraja1, Thallapuranam Krishnaswamy Suresh Kumar, Igor Prudovsky
1Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA.
Biochemical and Biophysical Research Communications
|August 27, 2005
Summary
The S100A13 protein
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biology
Background:
- S100A13 is a unique member of the S100 family of Ca2+-binding proteins.
- It plays a critical role in the non-classical export of signaling proteins like acidic fibroblast growth factors (FGFs-1).
Purpose of the Study:
- To determine the three-dimensional solution structure of Ca2+-bound S100A13.
- To elucidate the structural basis for S100A13's unique functions, particularly its interaction with FGF-1.
Main Methods:
- Three-dimensional Nuclear Magnetic Resonance (3D NMR) spectroscopy.
- Isothermal Titration Calorimetry (ITC).
Main Results:
- The globular structure of Ca2+-bound S100A13 was determined, featuring four helices and a beta-sheet per subunit.
- S100A13 binds non-cooperatively to four calcium ions.
- Unlike other S100 proteins, S100A13 lacks a hydrophobic pocket crucial for protein-protein interactions and possesses a distinct charge distribution.
- The C-terminal segment (residues 88-98) is essential for FGF-1 binding.
Conclusions:
- The unique structure of S100A13 provides insights into the non-classical export mechanism of signal peptide-less proteins like FGF-1.
- The findings support the development of targeted therapies against FGF-induced tumors.