Unique properties of the Mtr4p-poly(A) complex suggest a role in substrate targeting.
Biochemistry
; 49(49): 10357-70, 2010 Dec 14.
Article
em En
| MEDLINE
| ID: mdl-21058657
ABSTRACT
Mtr4p is a DEVH-box helicase required for 3'-end processing and degradation of various nuclear RNA substrates. In particular, Mtr4p is essential for the creation of 5.8S rRNA, U4 snRNA, and some snoRNAs and for the degradation of cryptic unstable transcripts (CUTs), aberrant mRNAs, and aberrant tRNAs. Many instances of 3'-end processing require limited polyadenylation to proceed. While polyadenylation can signal degradation in species from bacteria to humans, the mechanism whereby polyadenylated substrates are delivered to the degradation machinery is unknown. Our previous work has shown that Mtr4p preferentially binds poly(A) RNA. We suspect that this preference aids in targeting polyadenylated RNAs to the exosome. In these studies, we have investigated the mechanism underlying the preference of Mtr4p for poly(A) substrates as a means of understanding how Mtr4p might facilitate targeting. Our analysis has revealed that recognition of poly(A) substrates involves sequence-specific changes in the architecture of Mtr4p-RNA complexes. Furthermore, these differences significantly affect downstream activities. In particular, homopolymeric stretches like poly(A) ineffectively stimulate the ATPase activity of Mtr4p and suppress the rate of dissociation of the Mtr4p-RNA complex. These findings indicate that the Mtr4p-poly(A) complex is unique and ideally suited for targeting key substrates to the exosome.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Saccharomyces cerevisiae
/
Marcação de Genes
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Proteínas de Saccharomyces cerevisiae
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RNA Helicases DEAD-box
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article