title: Co-transcriptional formation of DNA:RNA hybrid G-quadruplex and potential function as constitutional cis element for transcription control.
abstract: G-quadruplex formation in genomic DNA is considered to regulate transcription. Previous investigations almost exclusively focused on intramolecular G-quadruplexes formed by DNA carrying four or more G-tracts, and structure formation has rarely been studied in physiologically relevant processes. Here, we report an almost entirely neglected, but actually much more prevalent form of G-quadruplexes, DNA:RNA hybrid G-quadruplexes (HQ) that forms in transcription. HQ formation requires as few as two G-tracts instead of four on a non-template DNA strand. Potential HQ sequences (PHQS) are present in >97% of human genes, with an average of 73 PHQSs per gene. HQ modulates transcription under both in vitro and in vivo conditions. Transcriptomal analysis of human tissues implies that maximal gene expression may be limited by the number of PHQS in genes. These features suggest that HQs may play fundamental roles in transcription regulation and other transcription-mediated processes.
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, PR China.
authors.forename: Ke-wei
authors.initials: KW
authors.lastname: Zheng
authors.forename: Shan
authors.initials: S
authors.lastname: Xiao
authors.forename: Jia-quan
authors.initials: JQ
authors.lastname: Liu
authors.forename: Jia-yu
authors.initials: JY
authors.lastname: Zhang
authors.forename: Yu-hua
authors.initials: YH
authors.lastname: Hao
authors.forename: Zheng
authors.initials: Z
authors.lastname: Tan
mesh_terms: D004247:DNA / Q000737:chemistry*; D054856:G-Quadruplexes; D015894:Genome, Human; D057809:HEK293 Cells; D006801:Humans; D010957:Plasmids / Q000235:genetics; D012313:RNA / Q000737:chemistry*; D050436:Regulatory Elements, Transcriptional; D014158:Transcription, Genetic; D059467:Transcriptome
chemical_list: D012313:RNA; D004247:DNA