Abstract
The folding mechanism of typical proteins has been studied widely, while our understanding of the origin of the high stability of thermophilic proteins is still elusive. Of particular interest is how an atypical thermophilic protein with a novel fold maintains its structure and stability under extreme conditions. Folding-unfolding transitions of MTH1880, a thermophilic protein from Methanobacterium thermoautotrophicum, induced by heat, urea, and GdnHCl, were investigated using spectroscopic techniques including circular dichorism, fluorescence, NMR combined with molecular dynamics (MD) simulations. Our results suggest that MTH1880 undergoes a two-state N to D transition and it is extremely stable against temperature and denaturants. The reversibility of refolding was confirmed by spectroscopic methods and size exclusion chromatography. We found that the hyper-stability of the thermophilic MTH1880 protein originates from an extensive network of both electrostatic and hydrophobic interactions coordinated by the central β-sheet. Spectroscopic measurements, in combination with computational simulations, have helped to clarify the thermodynamic and structural basis for hyper-stability of the novel thermophilic protein MTH1880.
Highlights
Folding mechanisms for a handful of proteins have been examined extensively using various techniques for a long time [1,2,3,4,5,6,7,8,9,10,11]
Our results imply that MTH1880 undergoes a large conformational change as the temperature changes from 25°C to 105°C
We found that (a) MTH1880 undergoes a reversible folding-unfolding process induced by urea, guanidine hydrochloride (GdnHCl) and temperature; (b) unfolding curves measured in the presence of urea or GdnHCl represented a two-state transition model; (c) β3-strand located in the middle of MTH1880 kept the native structure against the unfolding factors; and (d) urea denatured MTH1880 through a direct mechanism
Summary
Folding mechanisms for a handful of proteins have been examined extensively using various techniques for a long time [1,2,3,4,5,6,7,8,9,10,11]. Knowledge of folding-unfolding transitions between native and denatured conformations served in understanding protein’s biological function [19, 20]. Urea and guanidine hydrochloride (GdnHCl) are widely used as protein denaturing agents [21,22,23,24,25,26,27,28,29]. The mechanism how these denaturants disrupt protein structure could be either a direct or an indirect mechanism depending on a protein [30, 31]. Hyper-thermophilic and thermophilic proteins maintain structural stability under extreme
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
