Protein-mediated protection as the predominant mechanism for defining processed mRNA termini in land plant chloroplasts.
Nucleic Acids Res
; 40(7): 3092-105, 2012 Apr.
Article
en En
| MEDLINE
| ID: mdl-22156165
Most chloroplast mRNAs are processed from larger precursors. Several mechanisms have been proposed to mediate these processing events, including site-specific cleavage and the stalling of exonucleases by RNA structures. A protein barrier mechanism was proposed based on analysis of the pentatricopeptide repeat (PPR) protein PPR10: PPR10 binds two intercistronic regions and impedes 5'- and 3'-exonucleases, resulting in processed RNAs with PPR10 bound at the 5'- or 3'-end. In this study, we provide evidence that protein barriers are the predominant means for defining processed mRNA termini in chloroplasts. First, we map additional RNA termini whose arrangement suggests biogenesis via a PPR10-like mechanism. Second, we show that the PPR protein HCF152 binds to the immediate 5'- or 3'-termini of transcripts that require HCF152 for their accumulation, providing evidence that HCF152 defines RNA termini by blocking exonucleases. Finally, we build on the observation that the PPR10 and HCF152 binding sites accumulate as small chloroplast RNAs to infer binding sites of other PPR proteins. We show that most processed mRNA termini are represented by small RNAs whose sequences are highly conserved. We suggest that each such small RNA is the footprint of a PPR-like protein that protects the adjacent RNA from degradation.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas de Plantas
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ARN Mensajero
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Procesamiento Postranscripcional del ARN
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Proteínas de Unión al ARN
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ARN del Cloroplasto
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Regulación de la Expresión Génica de las Plantas
Idioma:
En
Revista:
Nucleic Acids Res
Año:
2012
Tipo del documento:
Article
País de afiliación:
Alemania
Pais de publicación:
Reino Unido