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.
Bibliographical noteFunding Information:
This work was funded by the Ministry of Future Creation and Science (MFCS) of Korea, the Translational Research Center for Protein Function Control (2009–0083522), and the Mid-career Researcher Program (2012–010285). HK, YJ, JY and JH were supported by a BK21plus program from the MFCS. It was also supported by the Creative Research Initiatives (Center for Proteome Biophysics) of National Research Foundation, Korea (No. 2008–0061984 to S.K, and I.C) and MIREBraiN program (I.C: No. 2015010013) from DGIST.
© 2016 Kim et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)
- Agricultural and Biological Sciences(all)