Molecular and Structural Insight into the Role of Key Residues of Thrombospondin-1 and Calreticulin in Thrombospondin-1鈭扖alreticulin Binding
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- 作者：Qi Yan ; Joanne E. Murphy-Ullrich ; Yuhua Song
- 刊名：Biochemistry
- 出版年：2011
- 出版时间：February 1, 2011
- 年：2011
- 卷：50
- 期：4
- 页码：566-573
- 全文大小：1065K
- 年卷期：v.50,no.4(February 1, 2011)
- ISSN：1520-4995
文摘
Thrombospondin-1 (TSP1) binding to calreticulin (CRT) on the cell surface signals focal adhesion disassembly, leading to the intermediate adhesive phenotype, cell migration, anoikis resistance, and collagen stimulation. Residues Lys 24 and 32 in TSP1 and amino acids 24鈭?6 and 32鈭?4 in CRT have been shown through biochemical and cell-based approaches to be critical for TSP1鈭扖RT binding and signaling. This study investigated the molecular and structural basis for these key TSP1 and CRT residues in TSP1鈭扖RT binding. On the basis of a validated TSP1鈭扖RT complex structure, we adopted steered molecular dynamics simulations to determine the effect of mutation of these key residues on TSP1鈭扖RT binding and validated the simulation results with experimental observations. We further performed 30 ns molecular dynamics simulations for wild-type TSP1, CRT, K24A/K32A mutant TSP1, and mutant CRT (residues 24鈭?6 and 32鈭?4 mutated to Ala) and studied the conformational and structural changes in TSP1 and CRT as the result of mutation of these critical residues. Results showed that mutation of residues 24 and 32 to Ala in TSP1 and of amino acids 24鈭?6 and 32鈭?4 to Ala in CRT results in a shortened 尾-strand in the binding site, decreased hydrogen bond occupancy for 尾-strand pairs that are located within or near the binding site, increased conformational flexibility of the binding site, a changed degree of dynamically correlated motion between the residues in the binding site and the other residues in protein, and a changed degree of overall correlated motion between the residues in the protein. These changes could directly contribute to the loss or weakened binding between TSP1 and CRT and the resultant effects on TSP1鈭扖RT binding-induced cellular activities. Results from this study provide a molecular and structural insight into the role of these critical residues of TSP1 and CRT in TSP1鈭扖RT binding.