Effect of DNA supercoiling on the geometry of holliday junctions.

ABSTRACT: Unusual DNA conformations including cruciforms play an important role in gene regulation and various DNA transactions. Cruciforms are also the models for Holliday junctions, the transient DNA conformations critically involved in DNA homologous and site-specific recombination, repair, and replication. Although the conformations of immobile Holliday junctions in linear DNA molecules have been analyzed with the use of various techniques, the role of DNA supercoiling has not been studied systematically. We utilized atomic force microscopy (AFM) to visualize cruciform geometry in plasmid DNA with different superhelical densities at various ionic conditions. Both folded and unfolded conformations of the cruciform were identified, and the data showed that DNA supercoiling shifts the equilibrium b

SUBMITTER: Mikheikin AL 

PROVIDER: S-EPMC1646289 | biostudies-literature | 2006 Oct

REPOSITORIES: biostudies-literature