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Literature DB >> 9321659

Winding of the DNA helix by divalent metal ions.

Abstract

When supercoiled pBR322 DNA was relaxed at 0 or 22 degrees C by topoisomerase I in the presence of the divalent cations Ca2+, Mn2+ or Co2+, the resulting distributions of topoisomers observed at 22 degrees C had positive supercoils, up to an average delta Lk value of +8.6 (for Ca2+at 0 degrees C), corresponding to an overwinding of the helix by 0.7 degrees/bp. An increase of the divalent cation concentration in the reaction mixture above 50 mM completely reversed the effect. When such ions were present in agarose electrophoresis gels, they caused a relaxation of positively supercoiled DNA molecules, and thus allowed a separation of strongly positively supercoiled topoisomers. The effect of divalent cations on DNA adds a useful tool for the study of DNA topoisomers, for the generation as well as separation of positively supercoiled DNA molecules.

Entities: Chemical

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Year: 1997 PMID： 9321659 PMCID： PMC147022 DOI： 10.1093/nar/25.20.4067

Source DB: PubMed Journal: Nucleic Acids Res ISSN： 0305-1048 Impact factor: 16.971

33 in total

10. In the absence of writhe, DNA relieves torsional stress with localized, sequence-dependent structural failure to preserve B-form.

Authors: Graham L Randall; Lynn Zechiedrich; B Montgomery Pettitt
Journal: Nucleic Acids Res Date: 2009-07-08 Impact factor: 16.971

Winding of the DNA helix by divalent metal ions.

1. Relative binding affinities of monovalent cations for double-stranded DNA.

2. Computer simulation of DNA supercoiling.

3. Transcription-driven supercoiling of DNA: direct biochemical evidence from in vitro studies.

4. Involement of supertwisted DNA in integrative recombination of bacteriophage lambda.

5. Influence of cation size and charge on the extrusion of a salt-dependent cruciform.

6. Transcription generates positively and negatively supercoiled domains in the template.

7. Knotting of a DNA chain during ring closure.

8. The helical repeat of DNA at high temperature.

9. Positively supercoiled plasmid DNA is produced by treatment of Escherichia coli with DNA gyrase inhibitors.

10. Direct visualization of supercoiled DNA molecules in solution.

1. Identification and characterization of the helix-destabilizing activity of rotavirus nonstructural protein NSP2.

2. Topoisomerase II, not topoisomerase I, is the proficient relaxase of nucleosomal DNA.

3. Electrostatic braiding and homologous pairing of DNA double helices.

4. K(+) , Na(+) , and Mg(2+) on DNA translocation in silicon nitride nanopores.

5. Short unligated sticky ends enable the observation of circularised DNA by atomic force and electron microscopies.

6. Helical chirality: a link between local interactions and global topology in DNA.

Review 7. Bullied no more: when and how DNA shoves proteins around.

8. Modelling and DNA topology of compact 2-start and 1-start chromatin fibres.

9. Local sensing of global DNA topology: from crossover geometry to type II topoisomerase processivity.

10. In the absence of writhe, DNA relieves torsional stress with localized, sequence-dependent structural failure to preserve B-form.