scholarly journals The Role of ATP in the RNA Translocation Mechanism of SARS-CoV-2 NSP13 Helicase

2021 ◽  
Author(s):  
Ryan Weber ◽  
Martin McCullagh
Keyword(s):  
Rational Design ◽  
Rna Binding ◽  
Gaussian Mixture ◽  
Dynamics Simulation ◽  
Dependent Manner ◽  
Structural Protein ◽  
Linear Discriminant ◽  
Translocation Mechanism ◽  
Key Aspects ◽  
Antiviral Targets

The COVID-19 pandemic has demonstrated the need to develop potent and transferable therapeutics to treat coronavirus infections. Numerous antiviral targets are being investigated, but non-structural protein 13 (nsp13) stands out as a highly conserved and yet under studied target. Nsp13 is a superfamily 1 (SF1) helicase that translocates along and unwinds viral RNA in an ATP dependent manner. Currently, there are no available structures of nsp13 from SARS-CoV-1 or SARS-CoV-2 with either ATP or RNA bound presenting a significant hurdle to the rational design of therapeutics. To address this knowledge gap, we have built models of SARS-CoV-2 nsp13 in Apo, ATP, ssRNA and ssRNA+ATP substrate states. Using 30 microseconds of Gaussian accelerated molecular dynamics simulation (at least 6 microseconds per substrate state), these models were confirmed to maintain substrate binding poses that are similar to other SF1 helicases. A gaussian mixture model and linear discriminant analysis structural clustering protocol was used to identify key aspects of the ATP-dependent RNA translocation mechanism. Namely, four RNA-nsp13 structures are identified that exhibit ATP-dependent populations and support the inch-worm mechanism for translocation. These four states are characterized by different RNA-binding poses for motifs Ia, IV, and V and suggest a powerstroke--like motion of domain 2A relative to domain 1A. This structural and mechanistic insight of nsp13 RNA translocation presents novel targets for the further development of antivirals.

scholarly journals Targeting of Non-Structural Protein 9 as a Novel Therapeutic Target for the Treatment of SARS-CoV-2

2020 ◽  
Vol 3 ◽  
Author(s):  
Matthew Anderson ◽  
John Turchi
Keyword(s):  
Viral Replication ◽  
Therapeutic Target ◽  
Rna Binding ◽  
Future Research ◽  
Great Promise ◽  
Dependent Manner ◽  
Nucleic Acid Binding ◽  
Structural Protein ◽  
Concentration Dependent Manner ◽  
Novel Therapeutic

Background/Hypothesis:  The 2019 novel coronavirus (SARS-CoV-2) is a human coronavirus responsible for a global pandemic with over 13 million confirmed cases. Currently, there are no treatments to block viral infection or replication. Exploring novel therapeutic targets for SARS-CoV-2 and future coronaviruses holds great promise for treating the current and future outbreaks. One such target is the non-structural protein 9 (nsp9), which has been shown to be highly conserved and unique to the coronavirus family as well as playing a role in viral replication. We hypothesize nsp9 is a viable target for therapeutic development.     Methods:  Towards determining the utility of targeting nsp9, a series of databases were queried for articles pertaining to nsp9 in SARS-CoV-2 and other coronaviruses and coronaviruses in general. We assessed structural, biochemical and cellular features of nsp9.      Results:  Nsp9 forms a homodimer via a conserved a-helix containing a glycine-rich interaction motif (GxxxG). Dimerization at the GxxxG interface is required for efficient viral replication. Nsp9’s core is an open, six-stranded b-barrel whose fold gives it a structure similar to nucleic acid binding OB-fold proteins. This OB-like fold has not been detected in replicative complexes of other RNA viruses and may reflect the unique and complex CoV replication machinery. Nsp9 is an indispensable component of the replication complex that binds single-stranded RNA in a concentration-dependent manner. A recent bioinformatic approach also found that nsp9 interacts with NF-kappa-B-repressing factor and may play a role in the IL-8/IL-6 mediated chemotaxis of neutrophils and inflammatory response observed in Covid-19 patients.     Conclusion/Potential Impact:   Based on this research, we conclude nsp9 represents a novel therapeutic target whose OB-like-fold may provide a targetable structure for interrupting RNA binding and impairing viral replication. This study will help inform current and future research that seeks to target nsp9’s structure and biochemical interactions as treatment for coronavirus infection. 

scholarly journals Interaction of 14-3-3I and CDPK1 mediates the growth of human malaria parasite

2020 ◽  
Author(s):  
Ravi Jain ◽  
Pinki Dey ◽  
Sakshi Gupta ◽  
Soumya Pati ◽  
Arnab Bhattacherjee ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Malaria Parasite ◽  
Rational Design ◽  
Physiological Role ◽  
Dynamics Simulation ◽  
Affinity Constant ◽  
Binding Motif ◽  
Dependent Manner ◽  
Simulation Studies

ABSTRACTScaffold proteins play pivotal role as modulators of cellular processes by operating as multipurpose conformation clamps. 14-3-3 proteins are gold-standard scaffold modules that recognize phosphoSer/Thr (pS/pT) containing conserved motifs of target proteins and confer conformational changes leading to modulation of their functional parameters. Modulation in functional activity of kinases has been attributed to their interaction with 14-3-3 proteins. Herein, we have characterized Plasmodium falciparum 14-3-3 and its interaction with key kinase of the parasite, Calcium-Dependent Protein Kinase 1 (CDPK1) by performing various analytical biochemistry and biophysical assays. Towards this, we annotated PF3D7_0818200 as 14-3-3 isoform I through extensive phylogenetic and comparative sequence analysis. Molecular dynamics simulation studies indicated that phosphoSer64 present in CDPK1 polypeptide sequence (61KLGpS64) behaves as canonical Mode I-type (RXXpS/pT) consensus 14-3-3 binding motif, mediating the interaction. The protein-protein interaction was validated in vitro with ELISA and SPR, which confirmed that CDPK1 interacts with 14-3-3I in a phosphorylation dependent manner, with binding affinity constant of 670 ± 3.6 nM. The interaction of 14-3-3I with CDPK1 was validated with well characterized optimal 14-3-3 recognition motifs: ARSHpSYPA and RLYHpSLPA as CDPK1 mimetics, by simulation studies and ITC. Further, interaction antagonizing peptidomimetics showed growth inhibitory impact on the parasite indicating crucial physiological role of 14-3-3/CDPK1 interaction. Overall, this study characterizes 14-3-3I as a scaffold protein in the malaria parasite and unveils CDPK1 as its previously unidentified target. This sets a precedent for the rational design of 14-3-3 based PPI inhibitors by utilizing 14-3-3 recognition motif peptides, as a potential antimalarial strategy.

scholarly journals Two mutations P/L and Y/C in SARS-CoV-2 helicase domain exist together and influence helicase RNA binding

2020 ◽  
Author(s):  
Feroza Begum ◽  
Arup Kumar Banerjee ◽  
Prem Prakash Tripathi ◽  
Upasana Ray
Keyword(s):  
Rna Binding ◽  
Rna Virus ◽  
Novel Mutation ◽  
Rna Replication ◽  
Viral Rna ◽  
Helicase Domain ◽  
Dependent Manner ◽  
Structural Protein ◽  
Rna Helicases ◽  
Rna Interaction

AbstractRNA helicases play pivotal role in RNA replication by catalysing the unwinding of complex RNA duplex structures into single strands in ATP/NTP dependent manner. SARS coronavirus 2 (SARS-CoV-2) is a single stranded positive sense RNA virus belonging to the family Coronaviridae. The viral RNA encodes non structural protein Nsp13 or the viral helicase protein that helps the viral RNA dependent RNA polymerase (RdRp) to execute RNA replication by unwinding the RNA duplexes. In this study we identified a novel mutation at position 541of the helicase where the tyrosine (Y) got substituted with cytosine (C). We found that Y541C is a destabilizing mutation increasing the molecular flexibility and leading to decreased affinity of helicase binding with RNA. Earlier we had reported a mutation P504L in the helicase protein for which had not performed RNA binding study. Here we report that P504L mutation leads to increased affinity of helicase RNA interaction. So, both these mutations have opposite effects on RNA binding. Moreover, we found a significant fraction of isolate population where both P504L and Y541C mutations were co-existing.

scholarly journals C9orf72-associated arginine-rich dipeptide repeats induce RNA-dependent nuclear accumulation of Staufen in neurons

2021 ◽  
Author(s):  
Eun Seon Kim ◽  
Chang Geon Chung ◽  
Jeong Hyang Park ◽  
Byung Su Ko ◽  
Sung Soon Park ◽  
...  
Keyword(s):  
Retinal Degeneration ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Nuclear Accumulation ◽  
Heterozygous Mutation ◽  
Pathological Feature ◽  
Dependent Manner ◽  
Cellular Processes ◽  
Drosophila Model ◽  
Post Transcriptional Regulation

Abstract RNA-binding proteins (RBPs) play essential roles in diverse cellular processes through post-transcriptional regulation of RNAs. The subcellular localization of RBPs is thus under tight control, the breakdown of which is associated with aberrant cytoplasmic accumulation of nuclear RBPs such as TDP-43 and FUS, well-known pathological markers for amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD). Here, we report in Drosophila model for ALS/FTD that nuclear accumulation of a cytoplasmic RBP, Staufen, may be a new pathological feature. We found that in Drosophila C4da neurons expressing PR36, one of the arginine-rich dipeptide repeat proteins (DPRs), Staufen accumulated in the nucleus in Importin- and RNA-dependent manner. Notably, expressing Staufen with exogenous NLS—but not with mutated endogenous NLS—potentiated PR-induced dendritic defect, suggesting that nuclear-accumulated Staufen can enhance PR toxicity. PR36 expression increased Fibrillarin staining in the nucleolus, which was enhanced by heterozygous mutation of stau (stau+/−), a gene that codes Staufen. Furthermore, knockdown of fib, which codes Fibrillarin, exacerbated retinal degeneration mediated by PR toxicity, suggesting that increased amount of Fibrillarin by stau+/− is protective. Stau+/− also reduced the amount of PR-induced nuclear-accumulated Staufen and mitigated retinal degeneration and rescued viability of flies expressing PR36. Taken together, our data show that nuclear accumulation of Staufen in neurons may be an important pathological feature contributing to the pathogenesis of ALS/FTD.

scholarly journals Propofol suppresses cell viability, cell cycle progression and motility and induces cell apoptosis of ovarian cancer cells through suppressing MEK/ERK signaling via targeting circVPS13C/miR-145 axis

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Huan Lu ◽  
Guanlin Zheng ◽  
Xiang Gao ◽  
Chanjuan Chen ◽  
Min Zhou ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Ovarian Cancer ◽  
Cancer Cells ◽  
Rna Binding ◽  
Erk Signaling ◽  
Luciferase Reporter ◽  
Migration And Invasion ◽  
Ovarian Cancer Cells ◽  
Dependent Manner ◽  
Vacuolar Protein

Abstract Background Propofol is a kind of common intravenous anaesthetic agent that plays an anti-tumor role in a variety of cancers, including ovarian cancer. However, the working mechanism of Propofol in ovarian cancer needs further exploration. Methods The viability and metastasis of ovarian cancer cells were assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and transwell assays. Flow cytometry was used to evaluate the cell cycle and apoptosis. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to examine the abundance of circular RNA vacuolar protein sorting 13 homolog C (circVPS13C) and microRNA-145 (miR-145). The target relationship between miR-145 and circVPS13C was predicted by circinteractome database and verified by dual-luciferase reporter assay, RNA-binding protein immunoprecipitation (RIP) assay and RNA-pull down assay. Western blot assay was used to detect the levels of phosphorylated extracellular regulated MAP kinase (p-ERK), ERK, p-MAP kinse-ERK kinase (p-MEK) and MEK, in ovarian cancer cells. Results Propofol treatment suppressed the viability, cell cycle and motility and elevated the apoptosis rate of ovarian cancer cells. Propofol up-regulated miR-145 in a dose-dependent manner. Propofol exerted an anti-tumor role partly through up-regulating miR-145. MiR-145 was a direct target of circVPS13C. Propofol suppressed the progression of ovarian cancer through up-regulating miR-145 via suppressing circVPS13C. Propofol functioned through circVPS13C/miR-145/MEK/ERK signaling in ovarian cancer cells. Conclusion Propofol suppressed the proliferation, cell cycle, migration and invasion and induced the apoptosis of ovarian cancer cells through circVPS13C/miR-145/MEK/ERK signaling in vitro.

The effect of amino substituents on the interactions of quinazolone derivatives with c-KIT G-quadruplex: insight from molecular dynamics simulation study for rational design of ligands

RSC Advances ◽  
2015 ◽  
Vol 5 (93) ◽  
pp. 76642-76650 ◽  
Author(s):  
Kiana Gholamjani Moghaddam ◽  
Seyed Majid Hashemianzadeh
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Simulation Study ◽  
Rational Design ◽  
Ligand Design ◽  
Dynamics Simulation ◽  
Rational Ligand Design ◽  
G Quadruplex ◽  
Ligand Interactions ◽  
Insight Into

Our study provides insight into the effect of different substituents on the G-quadruplex–ligand interactions which helps us rational ligand design.

scholarly journals Eukaryotic initiation factor EIF-3.G augments mRNA translation efficiency to regulate neuronal activity

2021 ◽  
Author(s):  
Stephen M Blazie ◽  
Seika Takayanagi-Kiya ◽  
Katherine A McCulloch ◽  
Yishi Jin
Keyword(s):  
Rna Binding ◽  
Mrna Translation ◽  
Initiation Factor ◽  
Translation Efficiency ◽  
Dependent Manner ◽  
Control Activity ◽  
C Elegans ◽  
Protein Levels ◽  
Neuronal Protein

AbstractThe translation initiation complex eIF3 imparts specialized functions to regulate protein expression. However, understanding of eIF3 activities in neurons remains limited despite widespread dysregulation of eIF3 subunits in neurological disorders. Here, we report a selective role of theC. elegansRNA-binding subunit EIF-3.G in shaping the neuronal protein landscape. We identify a missense mutation in the conserved Zinc-Finger (ZF) of EIF-3.G that acts in a gain-of-function manner to dampen neuronal hyperexcitation. Using neuron type-specific seCLIP, we systematically mapped EIF-3.G-mRNA interactions and identified EIF-3.G occupancy on GC-rich 5′UTRs of a select set of mRNAs enriched in activity-dependent functions. We demonstrate that the ZF mutation in EIF-3.G alters translation in a 5′UTR dependent manner. Our study reveals anin vivomechanism for eIF3 in governing neuronal protein levels to control activity states and offers insights into how eIF3 dysregulation contributes to neuronal disorders.

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