The challenge to the rule of homology modeling: folding mechanism study of protein G(A) and G(B) with high sequence identity but different native structures.
As one of the most valuable methods for drug design, homology modeling shows that protein structures are more conserved than protein sequences, that is, the proteins with high sequence identity have high structural similarity, but protein pairs G(A)88/G(B)88 and G(A)95/G(B)95 prove the opposite. The pairs G(A)88 and G(B)88 shares the 88% sequence identity, but display different structures, and the pair G(A)95 and G(B)95 with 95% sequence identity yet presents different structures. The research on these proteins provides an opportunity of complementary study. In the process of protein folding, at which stage the protein final structure was determined and which residues were important for folding to a given structure were still unknown. Here we used OPLS all-atom force field for molecular dynamics simulations to study the unfolding of G(A)88, G(B)88, G(A)95 and G(B)95 at high temperatures, and used the process of protein unfolding to reverse the process of protein folding. G(B)88 and G(B)95 folded to the α+β structure, but G(A)88 and G(A)95 folded to the all-α-helix structure. In the process of G(A)88 and G(A)95 folding, the helices folded earlier than the formation of tertiary interactions. In the process of folding to G(B)88 and G(B)95, the α-helix formed earlier. We showed that early along the folding pathway, the final protein structure was confirmed, and very small differences between protein sequences determined the protein structure.
Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Beijing 100049, PR China.
Xue
X
Wu
Zhong
Z
Jin
Zhilong
Z
Xiu
Guohui
G
Li
D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D019295:Computational Biology; D007700:Kinetics; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D017510:Protein Folding; D054730:Protein Interaction Domains and Motifs; D017386:Sequence Homology, Amino Acid; D040681:Structural Homology, Protein
D001426:Bacterial Proteins; C034284:IgG Fc-binding protein, Streptococcus; D010446:Peptide Fragments