{"title":"Molecular dynamics investigation of cysteine mutations: Effects on calcium ion affinity and structural stability in the RET cysteine-rich domain","authors":"Bithia. R, George Priya Doss C","doi":"10.1016/j.jmgm.2025.109072","DOIUrl":null,"url":null,"abstract":"<div><div>The RET receptor tyrosine kinase is essential for cell growth, differentiation, and survival. Its cysteine-rich domain (CRD) is crucial for ligand-induced dimerization, activation, and structural stability, significantly influenced by calcium ion coordination. Mutations in key cysteine residues can disrupt disulfide bonds, alter calcium binding, and destabilize the CRD, leading to oncogenic transformations. This study investigates the impact of cysteine mutations on calcium ion binding and the structural stability of the RET receptor's CRD. Using molecular dynamics simulations and free energy calculations, the research examines the structural effects of specific cysteine mutations (C565F, C581F, and C585S) in the CRD. The findings indicate that these mutations disrupt disulfide bonds, alter calcium binding, and destabilize the CRD. RMSD and RMSF analyses show that each mutant affects structural dynamics and flexibility differently. The C581F mutant exhibited the most significant effect, with average RMSD values of 0.21 nm compared to the wild-type (0.19 nm) and other mutants (C565F, 0.14 nm; C585S, 0.17 nm). Higher residue fluctuations were observed in C581F and C585S, particularly in the calcium-coordinating residues. Binding free energy analysis indicates reduced calcium-binding stability in the mutants, while weighted contact maps reveal altered residue interaction patterns and new contact formations. These results suggest that while global structural changes are minimal, cysteine mutations cause localized destabilization of calcium ion binding sites. The disruption of key disulfide bonds and reduced residue contacts likely contribute to decreased binding stability in the mutants, underscoring the importance of cysteine residues and calcium coordination in maintaining the integrity of the RET-CRD.</div></div>","PeriodicalId":16361,"journal":{"name":"Journal of molecular graphics & modelling","volume":"140 ","pages":"Article 109072"},"PeriodicalIF":3.0000,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of molecular graphics & modelling","FirstCategoryId":"99","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1093326325001329","RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"BIOCHEMICAL RESEARCH METHODS","Score":null,"Total":0}
引用次数: 0
Abstract
The RET receptor tyrosine kinase is essential for cell growth, differentiation, and survival. Its cysteine-rich domain (CRD) is crucial for ligand-induced dimerization, activation, and structural stability, significantly influenced by calcium ion coordination. Mutations in key cysteine residues can disrupt disulfide bonds, alter calcium binding, and destabilize the CRD, leading to oncogenic transformations. This study investigates the impact of cysteine mutations on calcium ion binding and the structural stability of the RET receptor's CRD. Using molecular dynamics simulations and free energy calculations, the research examines the structural effects of specific cysteine mutations (C565F, C581F, and C585S) in the CRD. The findings indicate that these mutations disrupt disulfide bonds, alter calcium binding, and destabilize the CRD. RMSD and RMSF analyses show that each mutant affects structural dynamics and flexibility differently. The C581F mutant exhibited the most significant effect, with average RMSD values of 0.21 nm compared to the wild-type (0.19 nm) and other mutants (C565F, 0.14 nm; C585S, 0.17 nm). Higher residue fluctuations were observed in C581F and C585S, particularly in the calcium-coordinating residues. Binding free energy analysis indicates reduced calcium-binding stability in the mutants, while weighted contact maps reveal altered residue interaction patterns and new contact formations. These results suggest that while global structural changes are minimal, cysteine mutations cause localized destabilization of calcium ion binding sites. The disruption of key disulfide bonds and reduced residue contacts likely contribute to decreased binding stability in the mutants, underscoring the importance of cysteine residues and calcium coordination in maintaining the integrity of the RET-CRD.
期刊介绍:
The Journal of Molecular Graphics and Modelling is devoted to the publication of papers on the uses of computers in theoretical investigations of molecular structure, function, interaction, and design. The scope of the journal includes all aspects of molecular modeling and computational chemistry, including, for instance, the study of molecular shape and properties, molecular simulations, protein and polymer engineering, drug design, materials design, structure-activity and structure-property relationships, database mining, and compound library design.
As a primary research journal, JMGM seeks to bring new knowledge to the attention of our readers. As such, submissions to the journal need to not only report results, but must draw conclusions and explore implications of the work presented. Authors are strongly encouraged to bear this in mind when preparing manuscripts. Routine applications of standard modelling approaches, providing only very limited new scientific insight, will not meet our criteria for publication. Reproducibility of reported calculations is an important issue. Wherever possible, we urge authors to enhance their papers with Supplementary Data, for example, in QSAR studies machine-readable versions of molecular datasets or in the development of new force-field parameters versions of the topology and force field parameter files. Routine applications of existing methods that do not lead to genuinely new insight will not be considered.