Intracellular transcription of G-rich DNAs induces formation of G-loops, novel structures containing G4 DNA
- 1Department of Genetics, Yale University School of Medicine, New Haven, Conneticut 06520, USA; 2Department of Immunology, 3Molecular and Cellular Biology Graduate Program, and 4Department of Biochemistry, University of Washington Medical School, Seattle, Washington 98195, USA; 5Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
Abstract
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.
Keywords
Footnotes
-
Article and publication are at http://www.genesdev.org/cgi/doi/10.1101/gad.1200804.
-
↵6 Corresponding author. E-MAIL maizels{at}u.washington.edu; FAX (206) 221-6781.
-
- Accepted May 7, 2004.
- Received March 5, 2004.
- Cold Spring Harbor Laboratory Press
