5'-UTR G-quadruplex structures acting as translational repressors.
Given that greater than 90% of the human genome is expressed, it is logical to assume that post-transcriptional regulatory mechanisms must be the primary means of controlling the flow of information from mRNA to protein. This report describes a robust approach that includes in silico, in vitro and in cellulo experiments permitting an in-depth evaluation of the impact of G-quadruplexes as translational repressors. Sequences including potential G-quadruplexes were selected within nine distinct genes encoding proteins involved in various biological processes. Their abilities to fold into G-quadruplex structures in vitro were evaluated using circular dichroism, thermal denaturation and the novel use of in-line probing. Six sequences were observed to fold into G-quadruplex structures in vitro, all of which exhibited translational inhibition in cellulo when linked to a reporter gene. Sequence analysis, direct mutagenesis and subsequent experiments were performed in order to define the rules governing the folding of G-quadruplexes. In addition, the impact of single-nucleotide polymorphism was shown to be important in the formation of G-quadruplexes located within the 5'-untranslated region of an mRNA. In light of these results, clearly the 5'-UTR G-quadruplexes represent a class of translational repressors that is broadly distributed in the cell.
Beaudoin
Jean-Denis
JD
RNA Group/Groupe ARN, Département de biochimie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, QC, J1H 5N4, Canada.
Perreault
Jean-Pierre
JP
D020121:5' Untranslated Regions; D054856:G-Quadruplexes; D006801:Humans; D014176:Protein Biosynthesis; D038621:Regulatory Sequences, Ribonucleic Acid
D020121:5' Untranslated Regions; D038621:Regulatory Sequences, Ribonucleic Acid