RESUMO
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the current coronavirus disease 2019 (COVID-19) pandemic. A major virulence factor of SARS-CoVs is the nonstructural protein 1 (Nsp1), which suppresses host gene expression by ribosome association. Here, we show that Nsp1 from SARS-CoV-2 binds to the 40S ribosomal subunit, resulting in shutdown of messenger RNA (mRNA) translation both in vitro and in cells. Structural analysis by cryo-electron microscopy of in vitro-reconstituted Nsp1-40S and various native Nsp1-40S and -80S complexes revealed that the Nsp1 C terminus binds to and obstructs the mRNA entry tunnel. Thereby, Nsp1 effectively blocks retinoic acid-inducible gene I-dependent innate immune responses that would otherwise facilitate clearance of the infection. Thus, the structural characterization of the inhibitory mechanism of Nsp1 may aid structure-based drug design against SARS-CoV-2.
Assuntos
Betacoronavirus/química , Evasão da Resposta Imune , Imunidade Inata , Biossíntese de Proteínas , Proteínas não Estruturais Virais/química , Proteínas não Estruturais Virais/metabolismo , Betacoronavirus/imunologia , Betacoronavirus/metabolismo , Betacoronavirus/fisiologia , Sítios de Ligação , COVID-19 , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/virologia , Microscopia Crioeletrônica , Proteína DEAD-box 58/genética , Proteína DEAD-box 58/metabolismo , Humanos , Interferon beta/genética , Interferon beta/metabolismo , Modelos Moleculares , Pandemias , Pneumonia Viral/imunologia , Pneumonia Viral/virologia , Ligação Proteica , Domínios Proteicos , Domínios e Motivos de Interação entre Proteínas , Estrutura Secundária de Proteína , RNA Mensageiro/metabolismo , Receptores Imunológicos , Subunidades Ribossômicas Menores de Eucariotos/química , Subunidades Ribossômicas Menores de Eucariotos/metabolismo , SARS-CoV-2RESUMO
The Java software jBar consists of a graphical user interface that allows the user to customize and assemble an included script for R. The scripted R pipeline calculates means and standard errors/deviations for replicates of numerical bivariate data and generates presentations in the form of bar graphs. A two-sided Student's t test is carried out against a user-selected reference and p-values are calculated. The user can enter the data conveniently through the built-in spreadsheet and configure the R pipeline in the graphical user interface. The configured R script is written into a file and then executed. Bar graphs can be generated as static PNG, PDF, and SVG files or as interactive HTML widgets. © 2019 International Union of Biochemistry and Molecular Biology, 47(2): 207-210, 2019.
