Chameleonicity and folding of the C-fragment of TOP7
Wayne County Community College District - Detroit, MI 48226, USA
2 Department of Physics, Michigan Technological University - Houghton, MI 49931, USA
3 Department of Chemistry & Biochemistry, University of Oklahoma - Norman, OK 73019, USA
Accepted: 14 February 2012
Using a specifically designed Go-model we have performed all-atom simulations of the C-fragment of TOP7. Our results support previous results (see Mohanty S. et al., Proc. Natl. Acad. Sci. U.S.A., 105 (2008) 8004; Mohanty S. and Hansmann U. H. E., J. Phys. Chem. B, 112 (2008) 15134) that indicate folding of this protein through configurations with non-native secondary structure. The N-terminal residues form first an extension of a subsequent α-helix, before finally refolding into a β-strand that completes a three-stranded β-sheet in the final structure. We show that mutations which reduce the “chameleonicity” of N-terminal residues (by increasing the propensity for “strandness” and reducing that for “helicity”) lead to folding into the same structure but with reduced folding rates and larger free-energy barriers.
PACS: 87.15.Cc – Folding: thermodynamics, statistical mechanics, models, and pathways / 87.15.hp – Conformational changes / 87.15.hm – Folding dynamics
© EPLA, 2012