title: The RING domain of the scaffold protein Ste5 adopts a molten globular character with high thermal and 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.
authors.affiliation: Institute of Molecular Biology and Biophysics, ETH Zürich, Otto-Stern-Weg 5, 8093 Zürich (Switzerland).
authors.forename: Michal J
authors.initials: MJ
authors.lastname: Walczak
authors.forename: Brighton
authors.initials: B
authors.lastname: Samatanga
authors.forename: Frank
authors.initials: F
authors.lastname: van Drogen
authors.forename: Matthias
authors.initials: M
authors.lastname: Peter
authors.forename: Ilian
authors.initials: I
authors.lastname: Jelesarov
authors.forename: Gerhard
authors.initials: G
authors.lastname: Wider
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000378:metabolism; D044387:GTP-Binding Protein beta Subunits / Q000737:chemistry / Q000378:metabolism; D044388:GTP-Binding Protein gamma Subunits / Q000737:chemistry / Q000378:metabolism; D008623:Mercaptoethanol / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D012965:Sodium Chloride / Q000737:chemistry; D013696:Temperature; D014508:Urea / Q000737:chemistry
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; C080321:STE5 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D012965:Sodium Chloride; D008623:Mercaptoethanol; D014508:Urea
keywords: NMR spectroscopy; biophysics; protein folding; signal transduction; structural biology