Retrospective on the all-in-one retroviral nucleocapsid protein

Darlix, Jean‐Luc; Rocquigny, Hugues de; Mauffret, Olivier; Mély, Yves

doi:10.1016/j.virusres.2014.05.011

Cited by 36 publications

(33 citation statements)

References 287 publications

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“…Indeed, NC is able to cover all HIV-1 RNA in the virion and this may occur in the cell when NC is included in Gag or GagPol or when it is partially cleaved by the protease. 71 These results also explain why, despite containing potent RSSs such as TAR and RRE described in this study, HIV-1 has not been observed to suppress RNAi. 16 Furthermore, when integrated, a self-inactivating lentivirus with no LTR will not express TAR or RRE, therefore confirming the use of RNAi as a valid therapeutic option to target HIV-1 in gene therapy.…”

Section: Discussionmentioning

confidence: 51%

HIV-1 RRE RNA acts as an RNA silencing suppressor by competing with TRBP-bound siRNAs

et al. 2015

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Several proteins and RNAs expressed by mammalian viruses have been reported to interfere with RNA interference (RNAi) activity. We investigated the ability of the HIV-1-encoded RNA elements Trans-Activation Response (TAR) and RevResponse Element (RRE) to alter RNAi. MicroRNA let7-based assays showed that RRE is a potent suppressor of RNAi activity, while TAR displayed moderate RNAi suppression. We demonstrate that RRE binds to TAR-RNA Binding Protein (TRBP), an essential component of the RNA Induced Silencing Complex (RISC). The binding of TAR and RRE to TRBP displaces small interfering (si)RNAs from binding to TRBP. Several stem-deleted RRE mutants lost their ability to suppress RNAi activity, which correlated with a reduced ability to compete with siRNA-TRBP binding. A lentiviral vector expressing TAR and RRE restricted RNAi, but RNAi was restored when Rev or GagPol were coexpressed. Adenoviruses are restricted by RNAi and encode their own suppressors of RNAi, the Virus-Associated (VA) RNA elements. RRE enhanced the replication of wild-type and VA-deficient adenovirus. Our work describes RRE as a novel suppressor of RNAi that acts by competing with siRNAs rather than by disrupting the RISC. This function is masked in lentiviral vectors co-expressed with viral proteins and thus will not affect their use in gene therapy. The potent RNAi suppressive effects of RRE identified in this study could be used to enhance the expression of RNAi restricted viruses used in oncolysis such as adenoviruses.

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Section: Discussionmentioning

confidence: 51%

HIV-1 RRE RNA acts as an RNA silencing suppressor by competing with TRBP-bound siRNAs

et al. 2015

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“…NC is involved in many steps of viral replication including virion assembly, genomic RNA packaging, reverse transcription and integration (Darlix et al, 2014). The CA protein constitutes the major structural protein of the virion core and plays a role in early events such as nuclear entry and DNA integration.…”

Section: Resultsmentioning

confidence: 99%

Histones Are Rapidly Loaded onto Unintegrated Retroviral DNAs Soon after Nuclear Entry

Wang

Goff

2016

Cell Host & Microbe

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Summary Chromosomal structure of nuclear DNA is usually maintained by insertion of nucleosomes into preexisting chromatin, both on newly synthesized DNA at replication forks and at sites of DNA damage. But during retrovirus infection, a histone-free DNA copy of the viral genome is synthesized that must be loaded with nucleosomes de novo. Here we show that core histones are rapidly loaded onto unintegrated Moloney murine leukemia virus DNAs. Loading of nucleosomes requires nuclear entry but does not require viral DNA integration. The histones associated with unintegrated DNAs become marked by covalent modifications, with a delay relative to the time of core histone loading. Expression from unintegrated DNA can be enhanced by modulation of the histone modifying machinery. The data show that histone loading onto unintegrated DNAs occurs very rapidly after nuclear entry and does not require prior establishment of an integrated provirus.

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“…NC exists as a domain of the Gag precursor protein and the partially matured products NCp15 and NCp9, which are generated by the retroviral protease (Mirambeau et al 2010). NC is involved in many steps in the HIV-1 replication cycle, including reverse transcription, selective genome packaging, genome dimerization, genome protection, and integration (Levin et al 2005Darlix et al 2007Darlix et al , 2011Darlix et al , 2014Sleiman et al 2012). During reverse transcription, the nucleic acid chaperone activity of NC facilitates the rearrangement of nucleic acids into their most thermodynamically stable structures.…”

Section: Introductionmentioning

confidence: 99%

Insights into the mechanisms of RNA secondary structure destabilization by the HIV-1 nucleocapsid protein

Belfetmi¹,

Zargarian²,

Tisné³

et al. 2016

RNA

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The mature HIV-1 nucleocapsid protein NCp7 (NC) plays a key role in reverse transcription facilitating the two obligatory strand transfers. Several properties contribute to its efficient chaperon activity: preferential binding to single-stranded regions, nucleic acid aggregation, helix destabilization, and rapid dissociation from nucleic acids. However, little is known about the relationships between these different properties, which are complicated by the ability of the protein to recognize particular HIV-1 stem-loops, such as SL1, SL2, and SL3, with high affinity and without destabilizing them. These latter properties are important in the context of genome packaging, during which NC is part of the Gag precursor. We used NMR to investigate destabilization of the full-length TAR (trans activating response element) RNA by NC, which is involved in the first strand transfer step of reverse transcription. NC was used at a low protein:nucleotide (nt) ratio of 1:59 in these experiments. NMR data for the imino protons of TAR identified most of the base pairs destabilized by NC. These base pairs were adjacent to the loops in the upper part of the TAR hairpin rather than randomly distributed. Gel retardation assays showed that conversion from the initial TAR-cTAR complex to the fully annealed form occurred much more slowly at the 1:59 ratio than at the higher ratios classically used. Nevertheless, NC significantly accelerated the formation of the initial complex at a ratio of 1:59.

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Retrospective on the all-in-one retroviral nucleocapsid protein

Cited by 36 publications

References 287 publications

HIV-1 RRE RNA acts as an RNA silencing suppressor by competing with TRBP-bound siRNAs

HIV-1 RRE RNA acts as an RNA silencing suppressor by competing with TRBP-bound siRNAs

Histones Are Rapidly Loaded onto Unintegrated Retroviral DNAs Soon after Nuclear Entry

Insights into the mechanisms of RNA secondary structure destabilization by the HIV-1 nucleocapsid protein

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