Folding of a transcriptionally acting preQ1 riboswitch.
Proc Natl Acad Sci U S A
; 107(24): 10804-9, 2010 Jun 15.
Article
em En
| MEDLINE
| ID: mdl-20534493
ABSTRACT
7-Aminomethyl-7-deazaguanine (preQ(1)) sensitive mRNA domains belong to the smallest riboswitches known to date. Although recent efforts have revealed the three-dimensional architecture of the ligand-aptamer complex less is known about the molecular details of the ligand-induced response mechanism that modulates gene expression. We present an in vitro investigation on the ligand-induced folding process of the preQ(1) responsive RNA element from Fusobacterium nucleatum using biophysical methods, including fluorescence and NMR spectroscopy of site-specifically labeled riboswitch variants. We provide evidence that the full-length riboswitch domain adopts two different coexisting stem-loop structures in the expression platform. Upon addition of preQ(1), the equilibrium of the competing hairpins is significantly shifted. This system therefore, represents a finely tunable antiterminator/terminator interplay that impacts the in vivo cellular response mechanism. A model is presented how a riboswitch that provides no obvious overlap between aptamer and terminator stem-loop solves this communication problem by involving bistable sequence determinants.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Pirimidinonas
/
Pirróis
/
RNA Bacteriano
/
RNA Mensageiro
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Áustria