{"title":"对 SARS-CoV-2 核头壳 C 端结构的 RNA 结合抑制剂的结构研究。","authors":"Preeti Dhaka, Jai Krishna Mahto, Ankur Singh, Pravindra Kumar, Shailly Tomar","doi":"10.1016/j.jsb.2025.108197","DOIUrl":null,"url":null,"abstract":"<div><div>The SARS-CoV-2 nucleocapsid (N) protein is an essential structural element of the virion, playing a crucial role in enclosing the viral genome into a ribonucleoprotein (RNP) assembly, as well as viral replication and transmission. The C-terminal domain of the N-protein (N-CTD) is essential for encapsidation, contributing to the stabilization of the RNP complex. In a previous study, three inhibitors (ceftriaxone, cefuroxime, and ampicillin) were screened for their potential to disrupt the RNA packaging process by targeting the N-protein. However, the binding efficacy, mechanism of RNA binding inhibition, and molecular insights of binding with N-CTD remain unclear. In this study, we evaluated the binding efficacy of these inhibitors using isothermal titration calorimetry (ITC), revealing the affinity of ceftriaxone (18 ± 1.3 μM), cefuroxime (55 ± 4.2 μM), and ampicillin (28 ± 1.2 μM) with the N-CTD. Further inhibition assay and fluorescence polarisation assay demonstrated RNA binding inhibition, with IC<sub>50</sub> ranging from ∼ 12 to 18 μM and K<sub>D</sub> values between 24 μM to 32 μM for the inhibitors, respectively. Additionally, we also determined the inhibitor-bound complex crystal structures of N-CTD-Ceftriaxone (2.0 Å) and N-CTD-Ampicillin (2.2 Å), along with the structure of apo N-CTD (1.4 Å). These crystal structures revealed previously unobserved interaction sites involving residues K261, K266, R293, Q294, and W301 at the oligomerization interface and the predicted RNA-binding region of N-CTD. These findings provide valuable molecular insights into the inhibition of N-CTD, highlighting its potential as an underexplored but promising target for the development of novel antiviral agents against coronaviruses.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108197"},"PeriodicalIF":3.0000,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Structural insights into the RNA binding inhibitors of the C-terminal domain of the SARS-CoV-2 nucleocapsid\",\"authors\":\"Preeti Dhaka, Jai Krishna Mahto, Ankur Singh, Pravindra Kumar, Shailly Tomar\",\"doi\":\"10.1016/j.jsb.2025.108197\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>The SARS-CoV-2 nucleocapsid (N) protein is an essential structural element of the virion, playing a crucial role in enclosing the viral genome into a ribonucleoprotein (RNP) assembly, as well as viral replication and transmission. The C-terminal domain of the N-protein (N-CTD) is essential for encapsidation, contributing to the stabilization of the RNP complex. In a previous study, three inhibitors (ceftriaxone, cefuroxime, and ampicillin) were screened for their potential to disrupt the RNA packaging process by targeting the N-protein. However, the binding efficacy, mechanism of RNA binding inhibition, and molecular insights of binding with N-CTD remain unclear. In this study, we evaluated the binding efficacy of these inhibitors using isothermal titration calorimetry (ITC), revealing the affinity of ceftriaxone (18 ± 1.3 μM), cefuroxime (55 ± 4.2 μM), and ampicillin (28 ± 1.2 μM) with the N-CTD. Further inhibition assay and fluorescence polarisation assay demonstrated RNA binding inhibition, with IC<sub>50</sub> ranging from ∼ 12 to 18 μM and K<sub>D</sub> values between 24 μM to 32 μM for the inhibitors, respectively. Additionally, we also determined the inhibitor-bound complex crystal structures of N-CTD-Ceftriaxone (2.0 Å) and N-CTD-Ampicillin (2.2 Å), along with the structure of apo N-CTD (1.4 Å). These crystal structures revealed previously unobserved interaction sites involving residues K261, K266, R293, Q294, and W301 at the oligomerization interface and the predicted RNA-binding region of N-CTD. These findings provide valuable molecular insights into the inhibition of N-CTD, highlighting its potential as an underexplored but promising target for the development of novel antiviral agents against coronaviruses.</div></div>\",\"PeriodicalId\":17074,\"journal\":{\"name\":\"Journal of structural biology\",\"volume\":\"217 2\",\"pages\":\"Article 108197\"},\"PeriodicalIF\":3.0000,\"publicationDate\":\"2025-03-18\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of structural biology\",\"FirstCategoryId\":\"99\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S1047847725000322\",\"RegionNum\":3,\"RegionCategory\":\"生物学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"BIOCHEMISTRY & MOLECULAR BIOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of structural biology","FirstCategoryId":"99","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1047847725000322","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
Structural insights into the RNA binding inhibitors of the C-terminal domain of the SARS-CoV-2 nucleocapsid
The SARS-CoV-2 nucleocapsid (N) protein is an essential structural element of the virion, playing a crucial role in enclosing the viral genome into a ribonucleoprotein (RNP) assembly, as well as viral replication and transmission. The C-terminal domain of the N-protein (N-CTD) is essential for encapsidation, contributing to the stabilization of the RNP complex. In a previous study, three inhibitors (ceftriaxone, cefuroxime, and ampicillin) were screened for their potential to disrupt the RNA packaging process by targeting the N-protein. However, the binding efficacy, mechanism of RNA binding inhibition, and molecular insights of binding with N-CTD remain unclear. In this study, we evaluated the binding efficacy of these inhibitors using isothermal titration calorimetry (ITC), revealing the affinity of ceftriaxone (18 ± 1.3 μM), cefuroxime (55 ± 4.2 μM), and ampicillin (28 ± 1.2 μM) with the N-CTD. Further inhibition assay and fluorescence polarisation assay demonstrated RNA binding inhibition, with IC50 ranging from ∼ 12 to 18 μM and KD values between 24 μM to 32 μM for the inhibitors, respectively. Additionally, we also determined the inhibitor-bound complex crystal structures of N-CTD-Ceftriaxone (2.0 Å) and N-CTD-Ampicillin (2.2 Å), along with the structure of apo N-CTD (1.4 Å). These crystal structures revealed previously unobserved interaction sites involving residues K261, K266, R293, Q294, and W301 at the oligomerization interface and the predicted RNA-binding region of N-CTD. These findings provide valuable molecular insights into the inhibition of N-CTD, highlighting its potential as an underexplored but promising target for the development of novel antiviral agents against coronaviruses.
期刊介绍:
Journal of Structural Biology (JSB) has an open access mirror journal, the Journal of Structural Biology: X (JSBX), sharing the same aims and scope, editorial team, submission system and rigorous peer review. Since both journals share the same editorial system, you may submit your manuscript via either journal homepage. You will be prompted during submission (and revision) to choose in which to publish your article. The editors and reviewers are not aware of the choice you made until the article has been published online. JSB and JSBX publish papers dealing with the structural analysis of living material at every level of organization by all methods that lead to an understanding of biological function in terms of molecular and supermolecular structure.
Techniques covered include:
• Light microscopy including confocal microscopy
• All types of electron microscopy
• X-ray diffraction
• Nuclear magnetic resonance
• Scanning force microscopy, scanning probe microscopy, and tunneling microscopy
• Digital image processing
• Computational insights into structure