scholarly journals Potential Achilles heels of SARS-CoV-2 displayed by the base order-dependent component of RNA folding energy

2020 ◽  
Author(s):  
Chiyu Zhang ◽  
Donald R. Forsdyke
Keyword(s):  
Rna Structure ◽  
Folding Energy ◽  
Packaging Signal ◽  
Antiviral Compound ◽  
N Protein ◽  
Gag Polyprotein ◽  
Protein Encoding ◽  
Dependent Component ◽  
High Base ◽  
Hiv 1

ABSTRACTBase order, not composition, best reflects local evolutionary pressure for folding of single-stranded nucleic acids. The base order-dependent component of folding energy has revealed a highly conserved region in HIV-1 genomes that associates with RNA structure. This corresponds to a packaging signal that is recognized by the nucleocapsid domain of the Gag polyprotein. Long viewed as a potential HIV-1 “Achilles heel,” the signal can be targeted by a recently described antiviral compound (NSC 260594) or by synthetic oligonucleotides. Thus, a conserved base-order-rich region of HIV-1 may facilitate therapeutic attack. Although SARS-CoV-2 differs in many respects from HIV-1, the same technology displays regions with a high base order-dependent folding energy component, which are also highly conserved. This indicates structural invariance (SI) sustained by natural selection. While the regions are often also protein-encoding (e.g. NSP3, ORF3a), we suggest that their nucleic acid level functions – such as the ribosomal frameshifting element (FSE) that facilitates differential expression of 1a and 1ab polyproteins – can be considered potential “Achilles heels” for SARS-CoV-2, perhaps susceptible to therapies like those envisaged for AIDS. The region of the FSE scored well, but higher SI scores were obtained in other regions, including those encoding NSP13 and the nucleocapsid (N) protein.

scholarly journals HIV-1 Packaging Visualised by In-Gel SHAPE

Viruses ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2389
Author(s):  
Aaron R. D’Souza ◽  
Dhivya Jayaraman ◽  
Ziqi Long ◽  
Jingwei Zeng ◽  
Liam J. Prestwood ◽  
...  
Keyword(s):  
Rna Structure ◽  
Structural Changes ◽  
Structural Protein ◽  
Packaging Signal ◽  
Packaging Process ◽  
Gag Polyprotein ◽  
Rna Conformation ◽  
Shape Selective ◽  
Insight Into ◽  
Hiv 1

HIV-1 packages two copies of its gRNA into virions via an interaction with the viral structural protein Gag. Both copies and their native RNA structure are essential for virion infectivity. The precise stepwise nature of the packaging process has not been resolved. This is largely due to a prior lack of structural techniques that follow RNA structural changes within an RNA–protein complex. Here, we apply the in-gel SHAPE (selective 2’OH acylation analysed by primer extension) technique to study the initiation of HIV-1 packaging, examining the interaction between the packaging signal RNA and the Gag polyprotein, and compare it with that of the NC domain of Gag alone. Our results imply interactions between Gag and monomeric packaging signal RNA in switching the RNA conformation into a dimerisation-competent structure, and show that the Gag–dimer complex then continues to stabilise. These data provide a novel insight into how HIV-1 regulates the translation and packaging of its genome.

The major HIV-1 packaging signal is an extended bulged stem loop whose structure is altered on interaction with the gag polyprotein

2000 ◽  
Vol 301 (5) ◽  
pp. 1315
Author(s):  
Amanda Zeffman ◽  
Stuart Hassard ◽  
Gabriele Varani ◽  
Andrew Lever
Keyword(s):  
Packaging Signal ◽  
Stem Loop ◽  
Gag Polyprotein ◽  
Hiv 1

scholarly journals Three-Dimensional RNA Structure of the Major HIV-1 Packaging Signal Region

Structure ◽  
2013 ◽  
Vol 21 (6) ◽  
pp. 951-962 ◽  
Author(s):  
James D. Stephenson ◽  
Haitao Li ◽  
Julia C. Kenyon ◽  
Martyn Symmons ◽  
Dave Klenerman ◽  
...  
Keyword(s):  
Rna Structure ◽  
Three Dimensional ◽  
Packaging Signal ◽  
Signal Region ◽  
Hiv 1

scholarly journals 5′-Cap sequestration is an essential determinant of HIV-1 genome packaging

2021 ◽  
Vol 118 (37) ◽  
pp. e2112475118
Author(s):  
Pengfei Ding ◽  
Siarhei Kharytonchyk ◽  
Nansen Kuo ◽  
Emily Cannistraci ◽  
Hana Flores ◽  
...  
Keyword(s):  
Rna Processing ◽  
Binding Sites ◽  
Rna Structure ◽  
Virus Assembly ◽  
Wild Type ◽  
Rna Packaging ◽  
Genome Packaging ◽  
Rna Dimerization ◽  
Gag Polyprotein ◽  
Hiv 1

HIV-1 selectively packages two copies of its 5′-capped RNA genome (gRNA) during virus assembly, a process mediated by the nucleocapsid (NC) domain of the viral Gag polyprotein and encapsidation signals located within the dimeric 5′ leader of the viral RNA. Although residues within the leader that promote packaging have been identified, the determinants of authentic packaging fidelity and efficiency remain unknown. Here, we show that a previously characterized 159-nt region of the leader that possesses all elements required for RNA dimerization, high-affinity NC binding, and packaging in a noncompetitive RNA packaging assay (ΨCES) is unexpectedly poorly packaged when assayed in competition with the intact 5′ leader. ΨCES lacks a 5′-tandem hairpin element that sequesters the 5′ cap, suggesting that cap sequestration may be important for packaging. Consistent with this hypothesis, mutations within the intact leader that expose the cap without disrupting RNA structure or NC binding abrogated RNA packaging, and genetic addition of a 5′ ribozyme to ΨCES to enable cotranscriptional shedding of the 5′ cap promoted ΨCES-mediated RNA packaging to wild-type levels. Additional mutations that either block dimerization or eliminate subsets of NC binding sites substantially attenuated competitive packaging. Our studies indicate that packaging is achieved by a bipartite mechanism that requires both sequestration of the 5′ cap and exposure of NC binding sites that reside fully within the ΨCES region of the dimeric leader. We speculate that cap sequestration prevents irreversible capture by the cellular RNA processing and translation machinery, a mechanism likely employed by other viruses that package 5′-capped RNA genomes.

scholarly journals The Zinc Content of HIV-1 NCp7 Affects Its Selectivity for Packaging Signal and Affinity for Stem-Loop 3

Viruses ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1922
Author(s):  
Ying Wang ◽  
Chao Guo ◽  
Xing Wang ◽  
Lianmei Xu ◽  
Rui Li ◽  
...  
Keyword(s):  
Rna Binding ◽  
Zinc Content ◽  
Binding Property ◽  
Zinc Ions ◽  
Packaging Signal ◽  
Stem Loop ◽  
Virus Maturation ◽  
Gag Polyprotein ◽  
Zinc Finger Motifs ◽  
Hiv 1

The nucleocapsid (NC) protein of human immunodeficiency (HIV) is a small, highly basic protein containing two CCHC zinc-finger motifs, which is cleaved from the NC domain of the Gag polyprotein during virus maturation. We previously reported that recombinant HIV-1 Gag and NCp7 overexpressed in an E. coli host contains two and one zinc ions, respectively, and Gag exhibited much higher selectivity for packaging signal (Psi) and affinity for the stem-loop (SL)-3 of Psi than NCp7. In this study, we prepared NCp7 containing 0 (0NCp7), 1 (NCp7) or 2 (2NCp7) zinc ions, and compared their secondary structure, Psi-selectivity and SL3-affinity. Along with the decrease of the zinc content, less ordered conformations were detected. Compared to NCp7, 2NCp7 exhibited a much higher Psi-selectivity and SL3-affinity, similar to Gag, whereas 0NCp7 exhibited a lower Psi-selectivity and SL3-affinity, similar to the H23&H44K double mutant of NCp7, indicating that the different RNA-binding property of Gag NC domain and the mature NCp7 may be resulted, at least partially, from their different zinc content. This study will be helpful to elucidate the critical roles that zinc played in the viral life cycle, and benefit further investigations of the functional switch from the NC domain of Gag to the mature NCp7.

scholarly journals Structure, Function, and Interactions of the HIV-1 Capsid Protein

Life ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 100
Author(s):  
Eric Rossi ◽  
Megan E. Meuser ◽  
Camille J. Cunanan ◽  
Simon Cocklin
Keyword(s):  
Life Cycle ◽  
Capsid Protein ◽  
Adaptor Proteins ◽  
Restriction Factors ◽  
Gag Polyprotein ◽  
Immunodeficiency Virus ◽  
Host Cell Factors ◽  
Hiv 1

The capsid (CA) protein of the human immunodeficiency virus type 1 (HIV-1) is an essential structural component of a virion and facilitates many crucial life cycle steps through interactions with host cell factors. Capsid shields the reverse transcription complex from restriction factors while it enables trafficking to the nucleus by hijacking various adaptor proteins, such as FEZ1 and BICD2. In addition, the capsid facilitates the import and localization of the viral complex in the nucleus through interaction with NUP153, NUP358, TNPO3, and CPSF-6. In the later stages of the HIV-1 life cycle, CA plays an essential role in the maturation step as a constituent of the Gag polyprotein. In the final phase of maturation, Gag is cleaved, and CA is released, allowing for the assembly of CA into a fullerene cone, known as the capsid core. The fullerene cone consists of ~250 CA hexamers and 12 CA pentamers and encloses the viral genome and other essential viral proteins for the next round of infection. As research continues to elucidate the role of CA in the HIV-1 life cycle and the importance of the capsid protein becomes more apparent, CA displays potential as a therapeutic target for the development of HIV-1 inhibitors.

scholarly journals Phenotypic Susceptibility to Bevirimat in Isolates from HIV-1-Infected Patients without Prior Exposure to Bevirimat

2010 ◽  
Vol 54 (6) ◽  
pp. 2345-2353 ◽  
Author(s):  
Nicolas A. Margot ◽  
Craig S. Gibbs ◽  
Michael D. Miller
Keyword(s):  
Recombinant Viruses ◽  
Gag Polyprotein ◽  
New Class ◽  
Major Mutation ◽  
Hiv Drugs ◽  
The Impact ◽  
First Time ◽  
Hiv 1

ABSTRACT Bevirimat (BVM) is the first of a new class of anti-HIV drugs with a novel mode of action known as maturation inhibitors. BVM inhibits the last cleavage of the Gag polyprotein by HIV-1 protease, leading to the accumulation of the p25 capsid-small peptide 1 (SP1) intermediate and resulting in noninfectious HIV-1 virions. Early clinical studies of BVM showed that over 50% of the patients treated with BVM did not respond to treatment. We investigated the impact of prior antiretroviral (ARV) treatment and/or natural genetic diversity on BVM susceptibility by conducting in vitro phenotypic analyses of viruses made from patient samples. We generated 31 recombinant viruses containing the entire gag and protease genes from 31 plasma samples from HIV-1-infected patients with (n = 21) or without (n = 10) prior ARV experience. We found that 58% of the patient isolates tested had a >10-fold reduced susceptibility to BVM, regardless of the patient's ARV experience or the level of isolate resistance to protease inhibitors. Analysis of mutants with site-directed mutations confirmed the role of the V370A SP1 polymorphism (SP1-V7A) in resistance to BVM. Furthermore, we demonstrated for the first time that a capsid polymorphism, V362I (CA protein-V230I), is also a major mutation conferring resistance to BVM. In contrast, none of the previously defined resistance-conferring mutations in Gag selected in vitro (H358Y, L363M, L363F, A364V, A366V, or A366T) were found to occur among the viruses that we analyzed. Our results should be helpful in the design of diagnostics for prediction of the potential benefit of BVM treatment in HIV-1-infected patients.

scholarly journals Correction: Normalization strategy for the LC-MS bioanalysis of protein kinetics assays via internal proteolytic analyte utilized as control standard: application in studies of HIV-1 protease cleavage of HIV-1 Gag polyprotein in HIV maturation inhibition research

2017 ◽  
Vol 9 (37) ◽  
pp. 5557-5557
Author(s):  
Joseph L. Cantone ◽  
Zeyu Lin ◽  
Ira B. Dicker ◽  
Dieter M. Drexler
Keyword(s):  
Protein Kinetics ◽  
Gag Polyprotein ◽  
Protease Cleavage ◽  
Normalization Strategy ◽  
Standard Application ◽  
Hiv 1

Correction for ‘Normalization strategy for the LC-MS bioanalysis of protein kinetics assays via internal proteolytic analyte utilized as control standard: application in studies of HIV-1 protease cleavage of HIV-1 Gag polyprotein in HIV maturation inhibition research’ by Joseph L. Cantone et al., Anal. Methods, 2017, DOI: 10.1039/c7ay01666b.

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