Structural #insights into #MERS and #SARS #coronavirus #membrane proteins

 

Abstract

The membrane (M) protein of coronaviruses is essential for maintaining structural integrity during membrane virion budding and viral pathogenesis. Given its high conservation in lineages within the betacoronavirus genus, such as sarbecoviruses, the M protein presents as an attractive therapeutic target; however, developing broad-spectrum antivirals targeting coronaviruses such as MERS-CoV is challenging due to lower sequence conservation and limited structural information available beyond that of the SARS-CoV-2 M protein. In this study, we report 3-3.2 Å resolution structures of MERS-CoV M protein, engineered with a SARS-CoV-2-like antibody interface, representing the first human merbecovirus M protein structure, and SARS-CoV M protein structures, with and without a previously identified SARS-CoV-2 M protein inhibitor, JNJ-9676. We highlight the structural differences between the MERS-CoV, SARS-CoV and SARS-CoV-2 M proteins, and present insights into the conservation of the JNJ-9676 binding pocket as well as key differences that could be targeted to accelerate the design of specific MERS-CoV and broad-spectrum antivirals targeting coronavirus M proteins.

Source: 

Link: https://www.nature.com/articles/s42003-025-09042-3

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#PA and #PAX: two key #proteins from segment 3 of the #influenza viruses

Abstract

In recent years, the influenza viruses have posed an increasingly severe threat to public health. It is essential to analyze the virulence and pathogenesis of influenza viruses to prevent and control them, as well as create antiviral drugs. Previous studies have revealed that influenza virus segment 3 codes for not only the PA protein but also a novel protein, PA-X. PA protein is one subunit of the polymerase of influenza viruses and plays a critical role in its life cycle. PA presented endonuclease activity, the transcription and replication of the viral genome, viral virulence, protein degradation, and host immune response by interacting with viral proteins, including PB2, PB1, and host factors, including ANP32A, CHD6, HAX1, hCLE, HDAC6, MCM complex. PA mutations were involved in the viral replication, pathogenicity, and transmission of influenza viruses in poultry, mammals, and humans. PA-X is an open reading frame generated by +1 ribosomal code shift at the N-terminal amino acids of segment 3 and possesses the shutoff activity of host gene expression, regulating the host immune response, viral virulence and transmission. Therefore, PA is one ideal target for the development of antiviral drugs against influenza viruses. Baloxavir marboxil (BXM) and Favipiravir are two very effective anti-influenza virus drugs targeting the PA endonuclease domain of influenza A viruses. In this review, we summarized the structures, viral replication, virulent determinants and transmission, host factors, innate immunity, and antiviral drugs involved in PA and PA-X. The information is of great value for underlying the mechanism of viral replication and developing novel effective strategies to prevent and control influenza infection and the pandemic.

Source: Frontiers in Cellucal and Infection Microbiology, https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2025.1560250/full

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