Intramolecular quadruplex formation of the G-rich strand of the mouse hypervariable minisatellite Pc-1.
The minisatellite Pc-1, isolated from the mouse genome consisting of a tandem repeat of d(GGCAG), is hypervariable with a mutation rate of 0.15/generation. Here we describe a structural characterization of the G-rich strand of Pc-1 by biochemical and physicochemical methods. It was found to be comparatively resistant to both single-stranded DNA-binding protein binding and digestion by single-stranded DNA-specific nuclease and to cause arrest of DNA synthesis. The guanine imino proton NMR signals observed on the Pc-1 G-rich strand and their slow (1)H/(2)H exchange profiles pointed to a quadruplex structure with guanine quartets. The melting temperature of the quadruplex determined by CD was not dependent on DNA concentration. These results indicate that the G-rich strand of Pc-1 forms an intramolecular folded-back quadruplex structure under physiological conditions. Possible mechanisms of the Pc-1 mutations implicated with the formation of the quadruplex structure are discussed.
Katahira
M
M
Department of Chemistry and Biotechnology, Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, 240, Japan.
Fukuda
H
H
Kawasumi
H
H
Sugimura
T
T
Nakagama
H
H
Nagao
M
M
D000818:Animals; D002942:Circular Dichroism; D004247:DNA / Q000096:biosynthesis; D004261:DNA Replication; D004276:DNA, Satellite / Q000737:chemistry*; D004277:DNA, Single-Stranded; D004591:Electrophoresis, Polyacrylamide Gel; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D018598:Minisatellite Repeats / Q000235:genetics*; D009154:Mutation; D009841:Oligonucleotides / Q000737:chemistry*; D015719:Single-Strand Specific DNA and RNA Endonucleases; D013696:Temperature; D013698:Templates, Genetic
D004276:DNA, Satellite; D004277:DNA, Single-Stranded; D009841:Oligonucleotides; D004247:DNA; D015719:Single-Strand Specific DNA and RNA Endonucleases