scholarly journals Structural basis of rotavirus RNA chaperone displacement and RNA annealing

2021 ◽  
Vol 118 (41) ◽  
pp. e2100198118
Author(s):  
Jack P. K. Bravo ◽  
Kira Bartnik ◽  
Luca Venditti ◽  
Julia Acker ◽  
Emma H. Gail ◽  
...  
Keyword(s):  
Virus Assembly ◽  
Rna Virus ◽  
Structural Proteomics ◽  
Structural Basis ◽  
Proteomics Data ◽  
Rna Chaperone ◽  
Rna Molecules ◽  
Cryo Electron Microscopy ◽  
Bacterial Rna ◽  
Rna Complex

Rotavirus genomes are distributed between 11 distinct RNA molecules, all of which must be selectively copackaged during virus assembly. This likely occurs through sequence-specific RNA interactions facilitated by the RNA chaperone NSP2. Here, we report that NSP2 autoregulates its chaperone activity through its C-terminal region (CTR) that promotes RNA–RNA interactions by limiting its helix-unwinding activity. Unexpectedly, structural proteomics data revealed that the CTR does not directly interact with RNA, while accelerating RNA release from NSP2. Cryo–electron microscopy reconstructions of an NSP2–RNA complex reveal a highly conserved acidic patch on the CTR, which is poised toward the bound RNA. Virus replication was abrogated by charge-disrupting mutations within the acidic patch but completely restored by charge-preserving mutations. Mechanistic similarities between NSP2 and the unrelated bacterial RNA chaperone Hfq suggest that accelerating RNA dissociation while promoting intermolecular RNA interactions may be a widespread strategy of RNA chaperone recycling.

scholarly journals Structural basis of rotavirus RNA chaperone displacement and RNA annealing

2020 ◽  
Author(s):  
Jack P. K. Bravo ◽  
Kira Bartnik ◽  
Luca Venditti ◽  
Emma H. Gail ◽  
Chen Davidovich ◽  
...  
Keyword(s):  
Virus Assembly ◽  
Rna Virus ◽  
Structural Proteomics ◽  
Structural Basis ◽  
Proteomics Data ◽  
Rna Chaperone ◽  
Rna Molecules ◽  
Cryo Electron Microscopy ◽  
Bacterial Rna ◽  
Rna Complex

AbstractRotavirus genomes are distributed between eleven distinct RNA molecules, all of which must be selectively co-packaged during virus assembly. This likely occurs through sequence-specific RNA interactions facilitated by the RNA chaperone NSP2. Here, we report that NSP2 auto-regulates its chaperone activity through its C-terminal region (CTR) that promotes RNA-RNA interactions by limiting its helix-unwinding activity. Unexpectedly, structural proteomics data revealed that the CTR does not directly interact with RNA, whilst accelerating RNA release from NSP2. Cryo-electron microscopy reconstructions of an NSP2-RNA complex reveal a highly conserved acidic patch poised towards RNA. Virus replication was abrogated by charge-disrupting mutations within the acidic patch but completely restored by charge-preserving mutations. Mechanistic similarities between NSP2 and the unrelated bacterial RNA chaperone Hfq suggest that accelerating RNA dissociation whilst promoting inter-molecular RNA interactions may be a widespread strategy of RNA chaperone recycling.

scholarly journals Structural basis of RNA recognition by the SARS-CoV-2 nucleocapsid phosphoprotein

2020 ◽  
Vol 16 (12) ◽  
pp. e1009100 ◽  
Author(s):  
Dhurvas Chandrasekaran Dinesh ◽  
Dominika Chalupska ◽  
Jan Silhan ◽  
Eliska Koutna ◽  
Radim Nencka ◽  
...  
Keyword(s):  
Rna Binding ◽  
Mutational Analysis ◽  
Rna Virus ◽  
Structural Basis ◽  
Rna Recognition ◽  
Nonstructural Proteins ◽  
Viral Membrane ◽  
Intrinsically Disordered ◽  
Binding Cleft ◽  
Rna Complex

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the coronavirus disease 2019 (COVID-19). SARS-CoV-2 is a single-stranded positive-sense RNA virus. Like other coronaviruses, SARS-CoV-2 has an unusually large genome that encodes four structural proteins and sixteen nonstructural proteins. The structural nucleocapsid phosphoprotein N is essential for linking the viral genome to the viral membrane. Both N-terminal RNA binding (N-NTD) and C-terminal dimerization domains are involved in capturing the RNA genome and, the intrinsically disordered region between these domains anchors the ribonucleoprotein complex to the viral membrane. Here, we characterized the structure of the N-NTD and its interaction with RNA using NMR spectroscopy. We observed a positively charged canyon on the surface of the N-NTD that might serve as a putative RNA binding site similarly to other coronaviruses. The subsequent NMR titrations using single-stranded and double-stranded RNA revealed a much more extensive U-shaped RNA-binding cleft lined with regularly distributed arginines and lysines. The NMR data supported by mutational analysis allowed us to construct hybrid atomic models of the N-NTD/RNA complex that provided detailed insight into RNA recognition.

scholarly journals Structural basis of RNA recognition by the SARS-CoV-2 nucleocapsid phosphoprotein

2020 ◽  
Author(s):  
Dhurvas Chandrasekaran Dinesh ◽  
Dominika Chalupska ◽  
Jan Silhan ◽  
Vaclav Veverka ◽  
Evzen Boura
Keyword(s):  
Global Economy ◽  
Rna Binding ◽  
Rna Virus ◽  
Structural Basis ◽  
Nonstructural Proteins ◽  
Virus Family ◽  
Viral Membrane ◽  
Rna Molecules ◽  
The Matrix ◽  
Arginine Residues

AbstractSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the Coronavirus disease 2019 (COVID-19) which is currently negatively affecting the population and disrupting the global economy. SARS-CoV-2 belongs to the +RNA virus family that utilize single-stranded positive-sense RNA molecules as genomes. SARS-CoV-2, like other coronaviruses, has an unusually large genome for a +RNA virus that encodes four structural proteins – the matrix (M), small envelope (E), spike (S) and nucleocapsid phosphoprotein (N) - and sixteen nonstructural proteins (nsp1-16) that together ensure replication of the virus in the host cell. The nucleocapsid phosphoprotein N is essential for linking the viral genome to the viral membrane. Its N-terminal RNA binding domain (N-NTD) captures the RNA genome while the C-terminal domain anchors the ribonucleoprotein complex to the viral membrane via its interaction with the M protein. Here, we characterized the structure of the N-NTD and its interaction with RNA using NMR spectroscopy. We observed a positively charged canyon on the surface of the N-NTD lined with arginine residues suggesting a putative RNA binding site. Next, we performed an NMR titration experiment using an RNA duplex. The observed changes in positions of signals in the N-NTD NMR spectra allowed us to construct a model of the N-NTD in complex with RNA.

scholarly journals Structural basis of transcription inhibition by the DNA mimic protein Ocr of bacteriophage T7

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Fuzhou Ye ◽  
Ioly Kotta-Loizou ◽  
Milija Jovanovic ◽  
Xiaojiao Liu ◽  
David TF Dryden ◽  
...  
Keyword(s):  
Restriction Enzymes ◽  
Structural Basis ◽  
Bacteriophage T7 ◽  
Transcription Inhibition ◽  
Modification System ◽  
Host Restriction ◽  
Restriction Modification System ◽  
Cryo Electron Microscopy ◽  
Bacterial Rna ◽  
Restriction Modification

Bacteriophage T7 infects Escherichia coli and evades the host restriction/modification system. The Ocr protein of T7 was shown to exist as a dimer mimicking DNA and to bind to host restriction enzymes, thus preventing the degradation of the viral genome by the host. Here we report that Ocr can also inhibit host transcription by directly binding to bacterial RNA polymerase (RNAP) and competing with the recruitment of RNAP by sigma factors. Using cryo electron microscopy, we determined the structures of Ocr bound to RNAP. The structures show that an Ocr dimer binds to RNAP in the cleft, where key regions of sigma bind and where DNA resides during transcription synthesis, thus providing a structural basis for the transcription inhibition. Our results reveal the versatility of Ocr in interfering with host systems and suggest possible strategies that could be exploited in adopting DNA mimicry as a basis for forming novel antibiotics.

scholarly journals Aptamer Applications in Emerging Viral Diseases

2021 ◽  
Vol 14 (7) ◽  
pp. 622
Author(s):  
Arne Krüger ◽  
Ana Paula de Jesus Santos ◽  
Vanessa de Sá ◽  
Henning Ulrich ◽  
Carsten Wrenger
Keyword(s):  
Virus Assembly ◽  
Viral Diseases ◽  
Tissue Penetration ◽  
Rna Molecules ◽  
Viral Particles ◽  
Pharmacokinetic Properties ◽  
Oligonucleotide Library ◽  
In Vivo Diagnosis ◽  
Emerging Viral Diseases

Aptamers are single-stranded DNA or RNA molecules which are submitted to a process denominated SELEX. SELEX uses reiterative screening of a random oligonucleotide library to identify high-affinity binders to a chosen target, which may be a peptide, protein, or entire cells or viral particles. Aptamers can rival antibodies in target recognition, and benefit from their non-proteic nature, ease of modification, increased stability, and pharmacokinetic properties. This turns them into ideal candidates for diagnostic as well as therapeutic applications. Here, we review the recent accomplishments in the development of aptamers targeting emerging viral diseases, with emphasis on recent findings of aptamers binding to coronaviruses. We focus on aptamer development for diagnosis, including biosensors, in addition to aptamer modifications for stabilization in body fluids and tissue penetration. Such aptamers are aimed at in vivo diagnosis and treatment, such as quantification of viral load and blocking host cell invasion, virus assembly, or replication, respectively. Although there are currently no in vivo applications of aptamers in combating viral diseases, such strategies are promising for therapy development in the future.

scholarly journals Structural basis for the regulation of nucleosome recognition and HDAC activity by histone deacetylase assemblies

2021 ◽  
Vol 7 (2) ◽  
pp. eabd4413
Author(s):  
Jung-Hoon Lee ◽  
Daniel Bollschweiler ◽  
Tillman Schäfer ◽  
Robert Huber
Keyword(s):  
Transcriptional Repression ◽  
Histone Deacetylases ◽  
Active Sites ◽  
Chromatin Modification ◽  
Structural Basis ◽  
Amino Terminal ◽  
Cryo Electron Microscopy ◽  
Multiple Contacts ◽  
Lysine Residues ◽  
Nucleosome Binding

The chromatin-modifying histone deacetylases (HDACs) remove acetyl groups from acetyl-lysine residues in histone amino-terminal tails, thereby mediating transcriptional repression. Structural makeup and mechanisms by which multisubunit HDAC complexes recognize nucleosomes remain elusive. Our cryo–electron microscopy structures of the yeast class II HDAC ensembles show that the HDAC protomer comprises a triangle-shaped assembly of stoichiometry Hda12-Hda2-Hda3, in which the active sites of the Hda1 dimer are freely accessible. We also observe a tetramer of protomers, where the nucleosome binding modules are inaccessible. Structural analysis of the nucleosome-bound complexes indicates how positioning of Hda1 adjacent to histone H2B affords HDAC catalysis. Moreover, it reveals how an intricate network of multiple contacts between a dimer of protomers and the nucleosome creates a platform for expansion of the HDAC activities. Our study provides comprehensive insight into the structural plasticity of the HDAC complex and its functional mechanism of chromatin modification.

scholarly journals The Core and Holoenzyme Forms of RNA Polymerase from Mycobacterium smegmatis

2018 ◽  
Vol 201 (4) ◽  
Author(s):  
Tomáš Kouba ◽  
Jiří Pospíšil ◽  
Jarmila Hnilicová ◽  
Hana Šanderová ◽  
Ivan Barvík ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rna Polymerase ◽  
Conformational Changes ◽  
Mycobacterium Smegmatis ◽  
Drug Target ◽  
Conformational Dynamics ◽  
Three Dimensional ◽  
Cryo Electron Microscopy ◽  
Bacterial Rna ◽  
High Degree

ABSTRACT Bacterial RNA polymerase (RNAP) is essential for gene expression and as such is a valid drug target. Hence, it is imperative to know its structure and dynamics. Here, we present two as-yet-unreported forms of Mycobacterium smegmatis RNAP: core and holoenzyme containing σA but no other factors. Each form was detected by cryo-electron microscopy in two major conformations. Comparisons of these structures with known structures of other RNAPs reveal a high degree of conformational flexibility of the mycobacterial enzyme and confirm that region 1.1 of σA is directed into the primary channel of RNAP. Taken together, we describe the conformational changes of unrestrained mycobacterial RNAP. IMPORTANCE We describe here three-dimensional structures of core and holoenzyme forms of mycobacterial RNA polymerase (RNAP) solved by cryo-electron microscopy. These structures fill the thus-far-empty spots in the gallery of the pivotal forms of mycobacterial RNAP and illuminate the extent of conformational dynamics of this enzyme. The presented findings may facilitate future designs of antimycobacterial drugs targeting RNAP.

scholarly journals Structural insights into the activation of human calcium-sensing receptor

2021 ◽  
Author(s):  
Xiaochen Chen ◽  
Lu Wang ◽  
Zhanyu Ding ◽  
Qianqian Cui ◽  
Li Han ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Large Scale ◽  
Transmembrane Domains ◽  
Structural Basis ◽  
Calcium Sensing Receptor ◽  
Calcium Sensing ◽  
Cryo Electron Microscopy ◽  
Activation Mechanisms ◽  
G Protein Coupled ◽  
Structural Insights

AbstractHuman calcium-sensing receptor (CaSR) is a G-protein-coupled receptor that maintains Ca2+ homeostasis in serum. Here, we present the cryo-electron microscopy structures of the CaSR in the inactive and active states. Complemented with previously reported crystal structures of CaSR extracellular domains, it suggests that there are three distinct conformations: inactive, intermediate and active state during the activation. We used a negative allosteric nanobody to stabilize the CaSR in the fully inactive state and found a new binding site for Ca2+ ion that acts as a composite agonist with L-amino acid to stabilize the closure of active Venus flytraps. Our data shows that the agonist binding leads to the compaction of the dimer, the proximity of the cysteine-rich domains, the large-scale transitions of 7-transmembrane domains, and the inter-and intrasubunit conformational changes of 7-transmembrane domains to accommodate the downstream transducers. Our results reveal the structural basis for activation mechanisms of the CaSR.

scholarly journals Structural basis of nucleic acid binding byNicotiana tabacumglycine-rich RNA-binding protein: implications for its RNA chaperone function

2014 ◽  
Vol 42 (13) ◽  
pp. 8705-8718 ◽  
Author(s):  
Fariha Khan ◽  
Mark A. Daniëls ◽  
Gert E. Folkers ◽  
Rolf Boelens ◽  
S. M. Saqlan Naqvi ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Structural Basis ◽  
Nucleic Acid Binding ◽  
Rna Chaperone ◽  
Chaperone Function

scholarly journals Cryo-EM structure of human mitochondrial trifunctional protein

2018 ◽  
Vol 115 (27) ◽  
pp. 7039-7044 ◽  
Author(s):  
Kai Liang ◽  
Ningning Li ◽  
Xiao Wang ◽  
Jianye Dai ◽  
Pulan Liu ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Oxidation Process ◽  
Structural Basis ◽  
Acid Oxidation ◽  
Cryo Electron Microscopy ◽  
Helical Hairpin ◽  
Tetrameric Structure ◽  
Acute Fatty Liver ◽  
Mitochondrial Trifunctional Protein

The mitochondrial trifunctional protein (TFP) catalyzes three reactions in the fatty acid β-oxidation process. Mutations in the two TFP subunits cause mitochondrial trifunctional protein deficiency and acute fatty liver of pregnancy that can lead to death. Here we report a 4.2-Å cryo-electron microscopy α2β2 tetrameric structure of the human TFP. The tetramer has a V-shaped architecture that displays a distinct assembly compared with the bacterial TFPs. A concave surface of the TFP tetramer interacts with the detergent molecules in the structure, suggesting that this region is involved in associating with the membrane. Deletion of a helical hairpin in TFPβ decreases its binding to the liposomes in vitro and reduces its membrane targeting in cells. Our results provide the structural basis for TFP function and have important implications for fatty acid oxidation related diseases.

Sign in / Sign up

Export Citation Format

Share Document