12 research outputs found
Short- and long-range interactions in the HIV-1 5âČ UTR regulate genome dimerization and packaging
RNA dimerization is the noncovalent association of two human immunodeficiency virus-1 (HIV-1) genomes. It is a conserved step in the HIV-1 life cycle and assumed to be a prerequisite for binding to the viral structural protein Pr55Gag during genome packaging. Here, we developed functional analysis of RNA structure-sequencing (FARS-seq) to comprehensively identify sequences and structures within the HIV-1 5âČ untranslated region (UTR) that regulate this critical step. Using FARS-seq, we found nucleotides important for dimerization throughout the HIV-1 5âČ UTR and identified distinct structural conformations in monomeric and dimeric RNA. In the dimeric RNA, key functional domains, such as stem-loop 1 (SL1), polyadenylation signal (polyA) and primer binding site (PBS), folded into independent structural motifs. In the monomeric RNA, SL1 was reconfigured into long- and short-range base pairings with polyA and PBS, respectively. We show that these interactions disrupt genome packaging, and additionally show that the PBSâSL1 interaction unexpectedly couples the PBS with dimerization and Pr55Gag binding. Altogether, our data provide insights into late stages of HIV-1 life cycle and a mechanistic explanation for the link between RNA dimerization and packaging.Peer Reviewe
Mechanism of selenoprotein mRNA 5'cap hypermethylation and impact on their translation
La synthĂšse des sĂ©lĂ©noprotĂ©ines fait appel Ă un mĂ©canisme de recodage traductionnel dâun codon UGASec. Chez les mammifĂšres, ce processus est conditionnĂ© par le recrutement de facteurs spĂ©cialisĂ©s dans la rĂ©gion 3âUTR des ARNm de sĂ©lĂ©noprotĂ©ines, au niveau dâune tige-boucle appelĂ©e SECIS. Lors de ma thĂšse, nous avons montrĂ© que certains ARNm de sĂ©lĂ©noprotĂ©ines possĂšdent une coiffe hypermĂ©thylĂ©e m32,2,7G Ă leur extrĂ©mitĂ© 5â, Ă la maniĂšre dâARN non-codants, et ne sont pas reconnus efficacement par le facteur canonique dâinitiation de la traduction eIF4E. Nous avons dĂ©terminĂ© le mĂ©canisme de biogenĂšse de cette coiffe qui fait appel Ă la TrimĂ©thyl-guanosine synthase, et avons montrĂ© que les ARNm de sĂ©lĂ©noprotĂ©ines coiffĂ©s m32,2,7G sont traduits in vivo. Par ailleurs, nos rĂ©sultats indiquent que lâinitiation de la traduction des ARNm de sĂ©lĂ©noprotĂ©ines suit un mĂ©canisme atypique qui ferait intervenir des Ă©lĂ©ments structuraux de lâARNm, la rĂ©gion 3âUTR et une GTPase encore inconnue.Selenoprotein synthesis requires co-translational recoding of in-frame UGA codons. In mammals, this process is governed by the recruitment of dedicated factors on a hairpin structure, called SECIS, in the 3âUTR of selenoprotein mRNAs. During my PhD, we showed that several selenoprotein mRNAs bear a hypermethylated m32,2,7G cap and undergo a similar 5â end maturation pathway than non-coding RNAs. This cap biogenesis mechanism involves the enzyme Trimethyl-guanosine synthase, m32,2,7G capped selenoprotein mRNAs are not efficiently recognized by the canonical translation initiation factor eIF4E but are translated in vivo. Furthermore, our results suggest the existence of an atypical mechanism of translation initiation for selenoprotein mRNAs. This process involves structural RNA determinants, the 3âUTR region and a GTPase that remains to be identified
Etude du mécanisme d'hyperméthylation de la coiffe des ARNm de sélénoprotéines et impact sur leur traduction
Selenoprotein synthesis requires co-translational recoding of in-frame UGA codons. In mammals, this process is governed by the recruitment of dedicated factors on a hairpin structure, called SECIS, in the 3âUTR of selenoprotein mRNAs. During my PhD, we showed that several selenoprotein mRNAs bear a hypermethylated m32,2,7G cap and undergo a similar 5â end maturation pathway than non-coding RNAs. This cap biogenesis mechanism involves the enzyme Trimethyl-guanosine synthase, m32,2,7G capped selenoprotein mRNAs are not efficiently recognized by the canonical translation initiation factor eIF4E but are translated in vivo. Furthermore, our results suggest the existence of an atypical mechanism of translation initiation for selenoprotein mRNAs. This process involves structural RNA determinants, the 3âUTR region and a GTPase that remains to be identified.La synthĂšse des sĂ©lĂ©noprotĂ©ines fait appel Ă un mĂ©canisme de recodage traductionnel dâun codon UGASec. Chez les mammifĂšres, ce processus est conditionnĂ© par le recrutement de facteurs spĂ©cialisĂ©s dans la rĂ©gion 3âUTR des ARNm de sĂ©lĂ©noprotĂ©ines, au niveau dâune tige-boucle appelĂ©e SECIS. Lors de ma thĂšse, nous avons montrĂ© que certains ARNm de sĂ©lĂ©noprotĂ©ines possĂšdent une coiffe hypermĂ©thylĂ©e m32,2,7G Ă leur extrĂ©mitĂ© 5â, Ă la maniĂšre dâARN non-codants, et ne sont pas reconnus efficacement par le facteur canonique dâinitiation de la traduction eIF4E. Nous avons dĂ©terminĂ© le mĂ©canisme de biogenĂšse de cette coiffe qui fait appel Ă la TrimĂ©thyl-guanosine synthase, et avons montrĂ© que les ARNm de sĂ©lĂ©noprotĂ©ines coiffĂ©s m32,2,7G sont traduits in vivo. Par ailleurs, nos rĂ©sultats indiquent que lâinitiation de la traduction des ARNm de sĂ©lĂ©noprotĂ©ines suit un mĂ©canisme atypique qui ferait intervenir des Ă©lĂ©ments structuraux de lâARNm, la rĂ©gion 3âUTR et une GTPase encore inconnue
Mechanism of selenoprotein mRNA 5'cap hypermethylation and impact on their translation
La synthĂšse des sĂ©lĂ©noprotĂ©ines fait appel Ă un mĂ©canisme de recodage traductionnel dâun codon UGASec. Chez les mammifĂšres, ce processus est conditionnĂ© par le recrutement de facteurs spĂ©cialisĂ©s dans la rĂ©gion 3âUTR des ARNm de sĂ©lĂ©noprotĂ©ines, au niveau dâune tige-boucle appelĂ©e SECIS. Lors de ma thĂšse, nous avons montrĂ© que certains ARNm de sĂ©lĂ©noprotĂ©ines possĂšdent une coiffe hypermĂ©thylĂ©e m32,2,7G Ă leur extrĂ©mitĂ© 5â, Ă la maniĂšre dâARN non-codants, et ne sont pas reconnus efficacement par le facteur canonique dâinitiation de la traduction eIF4E. Nous avons dĂ©terminĂ© le mĂ©canisme de biogenĂšse de cette coiffe qui fait appel Ă la TrimĂ©thyl-guanosine synthase, et avons montrĂ© que les ARNm de sĂ©lĂ©noprotĂ©ines coiffĂ©s m32,2,7G sont traduits in vivo. Par ailleurs, nos rĂ©sultats indiquent que lâinitiation de la traduction des ARNm de sĂ©lĂ©noprotĂ©ines suit un mĂ©canisme atypique qui ferait intervenir des Ă©lĂ©ments structuraux de lâARNm, la rĂ©gion 3âUTR et une GTPase encore inconnue.Selenoprotein synthesis requires co-translational recoding of in-frame UGA codons. In mammals, this process is governed by the recruitment of dedicated factors on a hairpin structure, called SECIS, in the 3âUTR of selenoprotein mRNAs. During my PhD, we showed that several selenoprotein mRNAs bear a hypermethylated m32,2,7G cap and undergo a similar 5â end maturation pathway than non-coding RNAs. This cap biogenesis mechanism involves the enzyme Trimethyl-guanosine synthase, m32,2,7G capped selenoprotein mRNAs are not efficiently recognized by the canonical translation initiation factor eIF4E but are translated in vivo. Furthermore, our results suggest the existence of an atypical mechanism of translation initiation for selenoprotein mRNAs. This process involves structural RNA determinants, the 3âUTR region and a GTPase that remains to be identified
Role of the SMN complex and the methylosome in selenoprotein mRNP assembly and translation
International audienc
Role of the SMN complex and the methylosome in selenoprotein mRNP assembly and translation
International audienc
RNA Structures and Their Role in Selective Genome Packaging.
To generate infectious viral particles, viruses must specifically select their genomic RNA from milieu that contains a complex mixture of cellular or non-genomic viral RNAs. In this review, we focus on the role of viral encoded RNA structures in genome packaging. We first discuss how packaging signals are constructed from local and long-range base pairings within viral genomes, as well as inter-molecular interactions between viral and host RNAs. Then, how genome packaging is regulated by the biophysical properties of RNA. Finally, we examine the impact of RNA packaging signals on viral evolution
SECIS-binding protein 2 interacts with the SMN complex and the methylosome for selenoprotein mRNP assembly and translation
International audienceSelenoprotein synthesis requires the co-translational recoding of a UGA Sec codon. This process involves an RNA structural element, called Selenocysteine Insertion Sequence (SECIS) and the SECIS binding protein 2 (SBP2). Several selenopro-tein mRNAs undergo unusual cap hypermethylation by the trimethylguanosine synthase 1 (Tgs1), which is recruited by the ubiquitous Survival of MotoNeu-rons (SMN) protein. SMN, the protein involved in spinal muscular atrophy, is part of a chaperone complex that collaborates with the methylosome for RNP assembly. Here, we analyze the role of individual SMN and methylosome components in selenoprotein mRNP assembly and translation. We show that SBP2 interacts directly with four proteins of the SMN complex and the methylosome core proteins. Nevertheless, SBP2 is not a methylation substrate of the methylosome. We found that both SMN and methylosome complexes are required for efficient translation of the selenoprotein GPx1 in vivo. We establish that the steady-state level of several selenoprotein mRNAs, major regulators of oxidative stress damage in neurons, is specifically reduced in the spinal cord of SMN-deficient mice and that cap hypermethylation of GPx1 mRNA is affected. Altogether we identified a new function of the SMN complex and the methylosome in selenoprotein mRNP assembly and expression