Intracellular transcription of G-rich DNAs induces formation of G-loops, novel structures containing G4 DNA.
We show that intracellular transcription of G-rich regions produces novel DNA structures, visible by electron microscopy as large (150-500 bp) loops. These G-loops are formed cotranscriptionally, and they contain G4 DNA on one strand and a stable RNA/DNA hybrid on the other. G-loop formation requires a G-rich nontemplate strand and reflects the unusual stability of the rG/dC base pair. G-loops and G4 DNA form efficiently within plasmid genomes transcribed in vitro or in Escherichia coli. These results establish that G4 DNA can form in vivo, a finding with implications for stability and maintenance of all G-rich genomic regions.
Duquette
Michelle L
ML
Department of Genetics, Yale University School of Medicine, New Haven, Conneticut 06520, USA.
Handa
Priya
P
Vincent
Jack A
JA
Taylor
Andrew F
AF
Maizels
Nancy
N
D020029:Base Pairing; D001483:Base Sequence; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000235:genetics; D012313:RNA / Q000737:chemistry / Q000235:genetics; D014158:Transcription, Genetic
D012313:RNA; D004247:DNA