title: Thermal stability and unfolding pathways of Sso7d and its mutant F31A: insight from molecular dynamics simulation.
abstract: The thermo-stability and unfolding behaviors of a small hyperthermophilic protein Sso7d as well as its single-point mutation F31A are studied by molecular dynamics simulation at temperatures of 300 K, 371 K and 500 K. Simulations at 300 K show that the F31A mutant displays a much larger flexibility than the wild type, which implies that the mutation obviously decreases the protein's stability. In the simulations at 371 K, although larger fluctuations were observed, both of these two maintain their stable conformations. High temperature simulations at 500 K suggest that the unfolding of these two proteins evolves along different pathways. For the wild-type protein, the C-terminal alpha-helix is melted at the early unfolding stage, whereas it is destroyed much later in the unfolding process of the F31A mutant. The results also show that the mutant unfolds much faster than its parent protein. The deeply buried aromatic cluster in the F31A mutant dissociates quickly relative to the wild-type protein at high temperature. Besides, it is found that the triple-stranded antiparallel β-sheet in the wild-type protein plays an important role in maintaining the stability of the entire structure.
authors.affiliation: College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, China.
authors.forename: Xianjin
authors.initials: X
authors.lastname: Xu
authors.forename: Jiguo
authors.initials: J
authors.lastname: Su
authors.forename: Weizu
authors.initials: W
authors.lastname: Chen
authors.forename: Cunxin
authors.initials: C
authors.lastname: Wang
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D056004:Molecular Dynamics Simulation; D050505:Mutant Proteins / Q000737:chemistry* / Q000378:metabolism*; D009154:Mutation; D055550:Protein Stability; D017433:Protein Structure, Secondary; D058767:Protein Unfolding; D013696:Temperature
chemical_list: D019843:Archaeal Proteins; D004268:DNA-Binding Proteins; D050505:Mutant Proteins; C093228:Sso7d protein, Sulfolobus