| Autor: |
Le Cam, Eric, Fack, Fred, Murcia, Josiane Ménissier-de, Cognet, Jean A.H., Barbin, Agnès, Sarantoglou, Vassilis, Révet, Bernard, Delain, Etienne, de Murcia, Gilbert |
| Zdroj: |
JMB Online (Journal of Molecular Biology); January 1994, Vol. 235 Issue: 3 p1062-1071, 10p |
| Abstrakt: |
The conformational changes induced by the introduction of a central and unique single-stranded break in a 139 base-pair DNA duplex have been analysed by means of polyacrylamide gel electrophoresis, HPLC and dark-field electron microscopy. Compared to the control DNA, the disruption of the covalent sugar-phosphate backbone induces a retardation detected both by gel electrophoresis and anion exchange based HPLC. Electron microscopic visualization of the DNA molecules reveals that most, of them present a central fracture at the position of the nick. Measures of the angle at the apex were very well fitted by a simple model of isotropic flexible junction assuming spatial Hooke's law and simple basic Boltzmann statistics. This amounts to using a folded Gaussian distribution. The fit yields an angle equilibrium value ϕ0= 122° for the nicked fragment. The angle distribution could also result from an equilibrium between two forms of the molecule with isotropic flexibility at the nicked site: a stacked and a very flexible unstacked form. The majority of bound poly(ADP-ribose) polymerase, a zinc-finger enzyme involved in DNA break detection, was localized at the apex of the V-shaped DNA duplex, with an accentuation of its general V -shaped conformation (ϕ0= 102°). |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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