title: The unusual and dynamic character of PX-DNA.
abstract: PX-DNA is a four-stranded DNA structure that has been implicated in the recognition of homology, either continuously, or in an every-other-half-turn fashion. Some of the structural features of the molecule have been noted previously, but the structure requires further characterization. Here, we report atomic force microscopic characterization of PX molecules that contain periodically placed biotin groups, enabling the molecule to be labeled by streptavidin molecules at these sites. In comparison with conventional double stranded DNA and with antiparallel DNA double crossover molecules, it is clear that PX-DNA is a more dynamic structure. Furthermore, the spacing between the nucleotide pairs along the helix axis is shorter, suggesting a mixed B/A structure. Circular dichroism spectroscopy indicates unusual features in the PX molecule that are absent in both the molecules to which it is compared.
authors.affiliation: Department of Chemistry, New York University, New York, NY 10003, USA.
authors.forename: Dong
authors.initials: D
authors.lastname: Niu
authors.affiliation: Department of Chemistry, New York University, New York, NY 10003, USA.
authors.forename: Hualin
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Department of Chemistry, New York University, New York, NY 10003, USA.
authors.forename: Ruojie
authors.initials: R
authors.lastname: Sha
authors.affiliation: Department of Chemistry, New York University, New York, NY 10003, USA.
authors.forename: James W
authors.initials: JW
authors.lastname: Canary
authors.affiliation: Department of Chemistry, New York University, New York, NY 10003, USA ned.seeman@nyu.edu.
authors.forename: Nadrian C
authors.initials: NC
authors.lastname: Seeman
mesh_terms: D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry* / Q000648:ultrastructure; D059371:DNA, B-Form / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D009690:Nucleic Acid Conformation
chemical_list: D059371:DNA, B-Form; D004247:DNA