title: Strand-Biased Formation of G-Quadruplexes in DNA Duplexes Transcribed with T7 RNA Polymerase.
abstract: G-quadruplex-forming sequences are enriched near transcription start sites (TSSs) in animal genes. They readily form G-quadruplexes in transcription, which in turn regulate transcription. Therefore, the control of G-quadruplex formation is important for their functionality. It is now shown that G-quadruplexes form efficiently on the non-template, but hardly on the template DNA strand in the downstream vicinity of TSSs in DNA duplexes when they are transcribed by the T7 RNA polymerase (RNAP). Structural analysis reveals that the T7 RNAP causes distortion in a DNA duplex both inside and in front of the enzyme. This structural distortion leads to strand-biased G-quadruplex formation when a G-quadruplex-forming sequence is partially fed into the T7 RNAP to a position about seven nucleotides away from the front of RNA synthesis. Based on these facts, we propose a model for the strand-biased formation of G-quadruplexes in transcribed DNA duplexes.
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 (P. R. China).
authors.forename: Jia-quan
authors.initials: JQ
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 (P. R. China).|Key Laboratory of Zebrafish Modeling and Drug Screening for Human Diseases of Guangdong Higher Education Institutes, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515 (P. R. China).
authors.forename: Shan
authors.initials: S
authors.lastname: Xiao
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 (P. R. China).
authors.forename: Yu-hua
authors.initials: YH
authors.lastname: Hao
authors.affiliation: State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 (P. R. China). z.tan@ioz.ac.cn.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Tan
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry*; D054856:G-Quadruplexes; D009696:Nucleic Acids; D014764:Viral Proteins / Q000737:chemistry*
chemical_list: D009696:Nucleic Acids; D014764:Viral Proteins; D004247:DNA; C062210:bacteriophage T7 RNA polymerase; D012321:DNA-Directed RNA Polymerases
keywords: DNA; G-quadruplexes; nucleic acids; secondary structure; transcription