A palindromic repeat sequence adopts a stable fold back structure under supercoiling
| Autor: | Arun K. Shukla, Kunal B. Roy |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Circular dichroism
Base Sequence Base pair Oligonucleotide Circular Dichroism fungi Palindrome General Medicine Biology G-Quartets Biochemistry Crystallography Duplex (building) DNA supercoil Nucleic Acid Conformation Molecular Biology Polyacrylamide gel electrophoresis Repetitive Sequences Nucleic Acid |
| Zdroj: | Journal of biochemistry. 139(1) |
| ISSN: | 0021-924X |
| Popis: | A synthetic deoxyoligonucleotide containing five palindromic repeats of GGATCC self assembles to form a parallel four-stranded structure held together by G-tetrads that shows slower mobility than duplex DNA. This structure is hypersensitive to S1 nuclease and resistant to DMS modification. The same oligonucleotide when cloned in a plasmid forms a different structure under supercoiling that persists stably even in the cleaved out insert. On polyacrylamide gel electrophoresis, the cleaved out insert moves to a position midway between the duplex and parallel four-stranded forms of the oligonucleotide. Upon S1 nuclease treatment, the cleaved out insert shows a discreet band of 18 base pairs, suggesting an unfolded region in the middle. All the guanines in the cleaved out insert are sensitive to DMS modification and produce a positive peak at 285 nM in the circular dichroism spectrum, a signature of fold back tetraplex structures. We propose a fold back quadruplex structure for the insert under supercoiling with only A.T.A.T and G.C.G.C tetrads. This is the first suggestive evidence of a general tetraplex motif without G quartets as that proposed for generalized recombination. |
| Databáze: | OpenAIRE |
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