1. The RING Domain of the Scaffold Protein Ste5 Adopts a Molten Globular Character with High Thermal and Chemical Stability
- Author
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Brighton Samatanga, Frank van Drogen, Ilian Jelesarov, Matthias Peter, Gerhard Wider, Michal J. Walczak, University of Zurich, and Walczak, Michal J
- Subjects
Scaffold protein ,Protein Folding ,Saccharomyces cerevisiae Proteins ,1503 Catalysis ,1600 General Chemistry ,Saccharomyces cerevisiae ,Sodium Chloride ,Catalysis ,03 medical and health sciences ,GTP-Binding Protein gamma Subunits ,10019 Department of Biochemistry ,Urea ,Nuclear Magnetic Resonance, Biomolecular ,Ste5 ,Adaptor Proteins, Signal Transducing ,Mercaptoethanol ,030304 developmental biology ,0303 health sciences ,Chemistry ,GTP-Binding Protein beta Subunits ,030302 biochemistry & molecular biology ,Temperature ,General Medicine ,General Chemistry ,Ligand (biochemistry) ,Molten globule ,Protein Structure, Tertiary ,Folding (chemistry) ,Crystallography ,Structural biology ,Biophysics ,570 Life sciences ,biology ,Protein folding ,Chemical stability - Abstract
Ste5 is a scaffold protein that controls the pheromone response of the MAP-kinase cascade in yeast cells. Upon pheromone stimulation, Ste5 (through its RING-H2 domain) interacts with the β and γ subunits of an activated heterodimeric G protein and promotes activation of the MAP-kinase cascade. With structural and biophysical studies, we show that the Ste5 RING-H2 domain exists as a molten globule under native buffer conditions, in yeast extracts, and even in denaturing conditions containing urea (7 M). Furthermore, it exhibits high thermal stability in native conditions. Binding of the Ste5 RING-H2 domain to the physiological Gβ/γ (Ste4/Ste18) ligand is accompanied by a conformational transition into a better folded, more globular structure. This study reveals novel insights into the folding mechanism and recruitment of binding partners by the Ste5 RING-H2 domain. We speculate that many RING domains may share a similar mechanism of substrate recognition and molten-globule-like character.
- Published
- 2013
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