Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 2 de 2
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Biol Chem ; 276(8): 5598-604, 2001 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-11092889

RESUMO

Although their genomes cannot be aligned at the nucleotide level, the HIV-1/SIVcpz and the HIV-2/SIVsm viruses are closely related lentiviruses that contain homologous functional and structural RNA elements in their 5'-untranslated regions. In both groups, the domains containing the trans-activating region, the 5'-copy of the polyadenylation signal, and the primer binding site (PBS) are followed by a short stem-loop (SL1) containing a six-nucleotide self-complementary sequence in the loop, flanked by unpaired purines. In HIV-1, SL1 is involved in the dimerization of the viral RNA, in vitro and in vivo. Here, we tested whether SL1 has the same function in HIV-2 and SIVsm RNA. Surprisingly, we found that SL1 is neither required nor involved in the dimerization of HIV-2 and SIV RNA. We identified the NarI sequence located in the PBS as the main site of HIV-2 RNA dimerization. cis and trans complementation of point mutations indicated that this self-complementary sequence forms symmetrical intermolecular interactions in the RNA dimer and suggested that HIV-2 and SIV RNA dimerization proceeds through a kissing loop mechanism, as previously shown for HIV-1. Furthermore, annealing of tRNA(3)(Lys) to the PBS strongly inhibited in vitro RNA dimerization, indicating that, in vivo, the intermolecular interaction involving the NarI sequence must be dissociated to allow annealing of the primer tRNA.


Assuntos
HIV-1/genética , HIV-2/genética , RNA Viral/metabolismo , Vírus da Imunodeficiência Símia/genética , Sítios de Ligação/genética , Dimerização , HIV-1/classificação , HIV-2/classificação , Modelos Genéticos , Mutagênese Sítio-Dirigida , Conformação de Ácido Nucleico , RNA de Transferência de Lisina , RNA Viral/química , Vírus da Imunodeficiência Símia/classificação
2.
RNA ; 5(9): 1222-34, 1999 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10496223

RESUMO

Retroviruses encapsidate their genome as a dimer of homologous RNA molecules noncovalently linked close to their 5' ends. The dimerization initiation site (DIS) of human immunodeficiency virus type 1 (HIV-1) RNA is a hairpin structure that contains in the loop a 6-nt self-complementary sequence flanked by two 5' and one 3' purines. The self-complementary sequence, as well as the flanking purines, are crucial for dimerization of HIV-1 RNA, which is mediated by formation of a "kissing-loop" complex between the DIS of each monomer. Here, we used chemical modification interference, lead-induced cleavage, and three-dimensional modeling to compare dimerization of subtype A and B HIV-1 RNAs. The DIS loop sequences of these RNAs are AGGUGCACA and AAGCGCGCA, respectively. In both RNAs, ethylation of most but not all phosphate groups in the loop and methylation of the N7 position of the G residues in the self-complementary sequence inhibited dimerization. These results demonstrate that small perturbations of the loop structure are detrimental to dimerization. Conversely, methylation of the N1 position of the first and last As in the loop were neutral or enhanced dimerization, a result consistent with these residues forming a noncanonical sheared base pair. Phosphorothioate interference, lead-induced cleavage, and Brownian-dynamics simulation revealed an unexpected difference in the dimerization mechanism of these RNAs. Unlike subtype B, subtype A requires binding of a divalent cation in the loop to promote RNA dimerization. This difference should be taken into consideration in the design of antidimerization molecules aimed at inhibiting HIV-1 replication.


Assuntos
Genoma Viral , HIV-1/genética , HIV-1/metabolismo , Magnésio/metabolismo , RNA/metabolismo , Sequência de Bases , Dimerização , Chumbo/metabolismo , Manganês/metabolismo , Metilação , Modelos Genéticos , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese , Conformação de Ácido Nucleico , Plasmídeos/metabolismo , RNA/síntese química , Tionucleotídeos/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...