Efficient transcription through an intron requires the binding of an Sm-type U1 snRNP with intact stem loop II to the splice donor.
Nucleic Acids Res
; 38(9): 3041-53, 2010 May.
Article
em En
| MEDLINE
| ID: mdl-20071748
ABSTRACT
The mechanism behind the positive action of introns upon transcription and the biological significance of this positive feedback remains unclear. Functional ablation of splice sites within an HIV-derived env cDNA significantly reduced transcription that was rescued by a U1 snRNA modified to bind to the mutated splice donor (SD). Using this model we further characterized both the U1 and pre-mRNA structural requirements for transcriptional enhancement. U1 snRNA rescued as a mature Sm-type snRNP with an intact stem loop II. Position and sequence context for U1-binding is crucial because a promoter proximal intron placed upstream of the mutated SD failed to rescue transcription. Furthermore, U1-rescue was independent of promoter and exon sequence and is partially replaced by the transcription elongation activator Tat, pointing to an intron-localized block in transcriptional elongation. Thus, transcriptional coupling of U1 snRNA binding to the SD may licence the polymerase for transcription through the intron.
Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Transcrição Gênica
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Íntrons
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Ribonucleoproteína Nuclear Pequena U1
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Sítios de Splice de RNA
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article