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The RING Domain of the Scaffold Protein Ste5 Adopts a Molten Globular Character with High Thermal and Chemical Stability
Author(s) -
Walczak Michal J.,
Samatanga Brighton,
van Drogen Frank,
Peter Matthias,
Jelesarov Ilian,
Wider Gerhard
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201306702
Subject(s) - scaffold protein , chemistry , biophysics , ring (chemistry) , molten globule , protein engineering , folding (dsp implementation) , scaffold , protein folding , stereochemistry , biochemistry , biology , signal transduction , enzyme , medicine , biomedical engineering , organic chemistry , electrical engineering , engineering
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.