Faculty Opinions recommendation of RNA 3'-end mismatch excision by the severe acute respiratory syndrome coronavirus nonstructural protein nsp10/nsp14 exoribonuclease complex.

Author(s):  
Stanley Perlman
2009 ◽  
Vol 83 (19) ◽  
pp. 10314-10318 ◽  
Author(s):  
Cromwell T. Cornillez-Ty ◽  
Lujian Liao ◽  
John R. Yates ◽  
Peter Kuhn ◽  
Michael J. Buchmeier

ABSTRACT The severe acute respiratory syndrome coronavirus (SARS-CoV) generates 16 nonstructural proteins (nsp's) through proteolytic cleavage of a large precursor protein. Although several nsp's exhibit catalytic activities that are important for viral replication and transcription, other nsp's have less clearly defined roles during an infection. In order to gain a better understanding of their functions, we attempted to identify host proteins that interact with nsp's during SARS-CoV infections. For nsp2, we identified an interaction with two host proteins, prohibitin 1 (PHB1) and PHB2. Our results suggest that nsp2 may be involved in the disruption of intracellular host signaling during SARS-CoV infections.


2015 ◽  
Vol 89 (23) ◽  
pp. 11820-11833 ◽  
Author(s):  
Justin K. Taylor ◽  
Christopher M. Coleman ◽  
Sandra Postel ◽  
Jeanne M. Sisk ◽  
John G. Bernbaum ◽  
...  

ABSTRACTSevere acute respiratory syndrome (SARS) emerged in November 2002 as a case of atypical pneumonia in China, and the causative agent of SARS was identified to be a novel coronavirus, severe acute respiratory syndrome coronavirus (SARS-CoV). Bone marrow stromal antigen 2 (BST-2; also known as CD317 or tetherin) was initially identified to be a pre-B-cell growth promoter, but it also inhibits the release of virions of the retrovirus human immunodeficiency virus type 1 (HIV-1) by tethering budding virions to the host cell membrane. Further work has shown that BST-2 restricts the release of many other viruses, including the human coronavirus 229E (hCoV-229E), and the genomes of many of these viruses encode BST-2 antagonists to overcome BST-2 restriction. Given the previous studies on BST-2, we aimed to determine if BST-2 has the ability to restrict SARS-CoV and if the SARS-CoV genome encodes any proteins that modulate BST-2's antiviral function. Through anin vitroscreen, we identified four potential BST-2 modulators encoded by the SARS-CoV genome: the papain-like protease (PLPro), nonstructural protein 1 (nsp1), ORF6, and ORF7a. As the function of ORF7a in SARS-CoV replication was previously unknown, we focused our study on ORF7a. We found that BST-2 does restrict SARS-CoV, but the loss of ORF7a leads to a much greater restriction, confirming the role of ORF7a as an inhibitor of BST-2. We further characterized the mechanism of BST-2 inhibition by ORF7a and found that ORF7a localization changes when BST-2 is overexpressed and ORF7a binds directly to BST-2. Finally, we also show that SARS-CoV ORF7a blocks the restriction activity of BST-2 by blocking the glycosylation of BST-2.IMPORTANCEThe severe acute respiratory syndrome coronavirus (SARS-CoV) emerged from zoonotic sources in 2002 and caused over 8,000 infections and 800 deaths in 37 countries around the world. Identifying host factors that regulate SARS-CoV pathogenesis is critical to understanding how this lethal virus causes disease. We have found that BST-2 is capable of restricting SARS-CoV release from cells; however, we also identified a SARS-CoV protein that inhibits BST-2 function. We show that the SARS-CoV protein ORF7a inhibits BST-2 glycosylation, leading to a loss of BST-2's antiviral function.


2004 ◽  
Vol 78 (22) ◽  
pp. 12218-12224 ◽  
Author(s):  
Kanchan Bhardwaj ◽  
Linda Guarino ◽  
C. Cheng Kao

ABSTRACT Nonstructural protein 15 (Nsp15) of the severe acute respiratory syndrome coronavirus (SARS-CoV) produced in Escherichia coli has endoribonuclease activity that preferentially cleaved 5′ of uridylates of RNAs. Blocking either the 5′ or 3′ terminus did not affect cleavage. Double- and single-stranded RNAs were both substrates for Nsp15 but with different kinetics for cleavage. Mn2+ at 2 to 10 mM was needed for optimal endoribonuclease activity, but Mg2+ and several other divalent metals were capable of supporting only a low level of activity. Concentrations of Mn2+ needed for endoribonuclease activity induced significant conformation change(s) in the protein, as measured by changes in tryptophan fluorescence. A similar endoribonucleolytic activity was detected for the orthologous protein from another coronavirus, demonstrating that the endoribonuclease activity of Nsp15 may be common to coronaviruses. This work presents an initial biochemical characterization of a novel coronavirus endoribonuclease.


2006 ◽  
Vol 80 (16) ◽  
pp. 7894-7901 ◽  
Author(s):  
Jeremiah S. Joseph ◽  
Kumar Singh Saikatendu ◽  
Vanitha Subramanian ◽  
Benjamin W. Neuman ◽  
Alexei Brooun ◽  
...  

ABSTRACT The severe acute respiratory syndrome coronavirus (SARS-CoV) possesses a large 29.7-kb positive-stranded RNA genome. The first open reading frame encodes replicase polyproteins 1a and 1ab, which are cleaved to generate 16 “nonstructural” proteins, nsp1 to nsp16, involved in viral replication and/or RNA processing. Among these, nsp10 plays a critical role in minus-strand RNA synthesis in a related coronavirus, murine hepatitis virus. Here, we report the crystal structure of SARS-CoV nsp10 at a resolution of 1.8 Å as determined by single-wavelength anomalous dispersion using phases derived from hexatantalum dodecabromide. nsp10 is a single domain protein consisting of a pair of antiparallel N-terminal helices stacked against an irregular β-sheet, a coil-rich C terminus, and two Zn fingers. nsp10 represents a novel fold and is the first structural representative of this family of Zn finger proteins found so far exclusively in coronaviruses. The first Zn finger coordinates a Zn2+ ion in a unique conformation. The second Zn finger, with four cysteines, is a distant member of the “gag-knuckle fold group” of Zn2+-binding domains and appears to maintain the structural integrity of the C-terminal tail. A distinct clustering of basic residues on the protein surface suggests a nucleic acid-binding function. Gel shift assays indicate that in isolation, nsp10 binds single- and double-stranded RNA and DNA with high-micromolar affinity and without obvious sequence specificity. It is possible that nsp10 functions within a larger RNA-binding protein complex. However, its exact role within the replicase complex is still not clear.


2019 ◽  
Vol 14 (5) ◽  
pp. 1934578X1984920 ◽  
Author(s):  
Andrew J. Staup ◽  
Ivon U. De Silva ◽  
Justin T. Catt ◽  
Xuan Tan ◽  
Robert G. Hammond ◽  
...  

Coronaviruses (CoVs) that cause infections such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome phylogenetically originate from bat CoVs. The coronaviral nonstructural protein 3 (nsp3) has been implicated in viral replication, polyprotein cleavage, and host immune interference. We report the structure of the C domain from the SARS-Unique Domain of bat CoV HKU4. The protein has a frataxin fold, consisting of 5 antiparallel β strands packed against 2 α helices. Bioinformatics analyses and nuclear magnetic resonance experiments were conducted to investigate the function of HKU4 C. The results showed that HKU4 C engages in protein-protein interactions with the nearby M domain of nsp3. The HKU4 C residues involved in protein-protein interactions are conserved in group 2c CoVs, indicating a conserved function.


2007 ◽  
Vol 81 (21) ◽  
pp. 12049-12060 ◽  
Author(s):  
Pedro Serrano ◽  
Margaret A. Johnson ◽  
Marcius S. Almeida ◽  
Reto Horst ◽  
Torsten Herrmann ◽  
...  

ABSTRACT This paper describes the structure determination of nsp3a, the N-terminal domain of the severe acute respiratory syndrome coronavirus (SARS-CoV) nonstructural protein 3. nsp3a exhibits a ubiquitin-like globular fold of residues 1 to 112 and a flexibly extended glutamic acid-rich domain of residues 113 to 183. In addition to the four β-strands and two α-helices that are common to ubiquitin-like folds, the globular domain of nsp3a contains two short helices representing a feature that has not previously been observed in these proteins. Nuclear magnetic resonance chemical shift perturbations showed that these unique structural elements are involved in interactions with single-stranded RNA. Structural similarities with proteins involved in various cell-signaling pathways indicate possible roles of nsp3a in viral infection and persistence.


2007 ◽  
Vol 81 (12) ◽  
pp. 6700-6708 ◽  
Author(s):  
Jeremiah S. Joseph ◽  
Kumar Singh Saikatendu ◽  
Vanitha Subramanian ◽  
Benjamin W. Neuman ◽  
Michael J. Buchmeier ◽  
...  

ABSTRACT Mature nonstructural protein-15 (nsp15) from the severe acute respiratory syndrome coronavirus (SARS-CoV) contains a novel uridylate-specific Mn2+-dependent endoribonuclease (NendoU). Structure studies of the full-length form of the obligate hexameric enzyme from two CoVs, SARS-CoV and murine hepatitis virus, and its monomeric homologue, XendoU from Xenopus laevis, combined with mutagenesis studies have implicated several residues in enzymatic activity and the N-terminal domain as the major determinant of hexamerization. However, the tight link between hexamerization and enzyme activity in NendoUs has remained an enigma. Here, we report the structure of a trimmed, monomeric form of SARS-CoV nsp15 (residues 28 to 335) determined to a resolution of 2.9 Å. The catalytic loop (residues 234 to 249) with its two reactive histidines (His 234 and His 249) is dramatically flipped by ∼120° into the active site cleft. Furthermore, the catalytic nucleophile Lys 289 points in a diametrically opposite direction, a consequence of an outward displacement of the supporting loop (residues 276 to 295). In the full-length hexameric forms, these two loops are packed against each other and are stabilized by intimate intersubunit interactions. Our results support the hypothesis that absence of an adjacent monomer due to deletion of the hexamerization domain is the most likely cause for disruption of the active site, offering a structural basis for why only the hexameric form of this enzyme is active.


2021 ◽  
Vol 12 ◽  
Author(s):  
Chengdong Zhang ◽  
Xuanxuan Jin ◽  
Xianyang Chen ◽  
Li Qiu ◽  
Qibin Leng ◽  
...  

The mutation pattern of severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) has changed constantly during worldwide community transmission of this virus. However, the reasons for the changes in mutation patterns are still unclear. Accordingly, in this study, we present a comprehensive analysis of over 300 million peptides derived from 13,432 SARS-CoV-2 strains harboring 4,420 amino acid mutations to analyze the potential selective pressure of the host immune system and reveal the driver of mutations in circulating SARS-CoV-2 isolates. The results showed that the nonstructural protein ORF1ab and the structural protein Spike were most susceptible to mutations. Furthermore, mutations in cross-reactive T-cell epitopes between SARS-CoV-2 and seasonal human coronavirus may help SARS-CoV-2 to escape cellular immunity under long-term and large-scale community transmission. Additionally, through homology modeling and protein docking, mutations in Spike protein may enhance the ability of SARS-CoV-2 to invade host cells and escape antibody-mediated B-cell immunity. Our research provided insights into the potential mutation patterns of SARS-CoV-2 under natural selection, improved our understanding of the evolution of the virus, and established important guidance for potential vaccine design.


2021 ◽  
Author(s):  
Ali Rahnavard ◽  
Rebecca Clement ◽  
Nathaniel Stearrett ◽  
Marcos Pérez-Losada ◽  
Keith A. Crandall ◽  
...  

Abstract The 2019 novel coronavirus (SARS-CoV-2) is the etiological agent of the COVID-19 pandemic and evolves to evade both host immune systems and intervention strategies. To diminish the short-term and long-term impacts of coronavirus (CoV), we investigated CoV differences at the nucleotide and protein level and CoV genomic variation associated with epidemiological variation and geography. We divided the CoV genome into 29 constituent regions for this analysis. Our results highlight the variation of CoV variants of lineage and show that nonstructural protein 3 (nsp3) and Spike protein (S) have the highest variation and greatest correlation with the viral whole-genome variation, which makes these two proteins potential targets for treatments. S protein variation is highly correlated with nsp3, nsp6, and 3'−to−5' exonuclease. Country of origin and time since the start of the pandemic were the most influential metadata in these differences. Host sex and age are the lowest in terms of explaining the virus genome variation. We quantified variation explained by regions of the CoV genome across different CoV viruses including, SARS-CoV-2, Middle East respiratory syndrome coronavirus (MERS-CoV), other severe acute respiratory syndrome coronavirus SARS-CoV (SARS-related), and bat-derived severe acute respiratory syndrome (SARS)-like coronaviruses (Bat-SL-CoV). We found that Spike protein and nsp3 explain most of the variation among these viruses; they are also among the genomic regions with the highest number of sites under natural selection. Our results provide a direction to prioritize genes associated with outcome predictors, including health, therapeutic, and vaccine outcomes, and to inform improved DNA tests for predicting disease status.


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