title: A stable RNA G-quadruplex within the 5'-UTR of Arabidopsis thaliana ATR mRNA inhibits translation.
abstract: Guanine quadruplex structures (GQSs) play important roles in the regulation of gene expression and cellular processes. Recent studies provide strong evidence for the formation and function of DNA and RNA GQSs in human cells. However, whether GQSs form and are functional in plants remains essentially unexplored. On the basis of circular dichroism (CD)-detected titration, UV-detected melting, in-line probing (ILP) and reporter gene assay studies, we report the first example of a plant RNA GQS that inhibits translation. This GQS is located within the 5'-UTR of the ATAXIA TELANGIECTASIA-MUTATED AND RAD3-RELATED (ATR) mRNA of Arabidopsis thaliana (mouse-ear cress). We show that this GQS is highly stable and is thermodynamically favoured over a competing hairpin structure in the 5'-UTR at physiological K⁺ and Mg²⁺ concentrations. Results from ILP reveal the secondary structure of the RNA and support formation of the GQS in vitro in the context of the complete 5'-UTR. Transient reporter gene assays performed in living plants reveal that the GQS inhibits translation but not transcription, implicating this GQS as a translational repressor in vivo. Our results provide the first complete demonstration of the formation and function of a regulatory RNA GQS in plants and open new avenues to explore potential functional roles of GQS in the plant kingdom.
authors: *Department of Chemistry, Pennsylvania State University, University Park, PA 16802, U.S.A.
authors: Chun Kit
authors: CK
authors: Kwok
authors: *Department of Chemistry, Pennsylvania State University, University Park, PA 16802, U.S.A.
authors: Yiliang
authors: Y
authors: Ding
authors: †Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802, U.S.A.
authors: Saima
authors: S
authors: Shahid
authors: †Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802, U.S.A.
authors: Sarah M
authors: SM
authors: Assmann
authors: *Department of Chemistry, Pennsylvania State University, University Park, PA 16802, U.S.A.
authors: Philip C
authors: PC
authors: Bevilacqua
mesh_terms: D020121:5' Untranslated Regions; D017360:Arabidopsis / Q000201:enzymology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics / Q000378:metabolism*; D002942:Circular Dichroism; D004274:DNA, Recombinant / Q000737:chemistry / Q000378:metabolism; D015536:Down-Regulation; D054856:G-Quadruplexes; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D055029:Inverted Repeat Sequences; D009154:Mutation; D009691:Nucleic Acid Denaturation; D018515:Plant Leaves / Q000378:metabolism; D014176:Protein Biosynthesis; D059370:RNA Folding; D020871:RNA Stability; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism*; D018749:RNA, Plant / Q000737:chemistry / Q000378:metabolism*; D013045:Species Specificity; D014026:Nicotiana / Q000378:metabolism
chemical_list: D020121:5' Untranslated Regions; D029681:Arabidopsis Proteins; D004274:DNA, Recombinant; D012333:RNA, Messenger; D018749:RNA, Plant; C576892:ATR protein, Arabidopsis; D064007:Ataxia Telangiectasia Mutated Proteins