These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Mediation of the A/B-DNA helix transition by G-tracts in the crystal structure of duplex CATGGGCCCATG.
    Author: Ng HL, Dickerson RE.
    Journal: Nucleic Acids Res; 2002 Sep 15; 30(18):4061-7. PubMed ID: 12235390.
    Abstract:
    The crystal structure of the DNA dodecamer duplex CATGGGCCCATG lies on a structural continuum along the transition between A- and B-DNA. The dodecamer possesses the normal vector plot and inclination values typical of B-DNA, but has the crystal packing, helical twist, groove width, sugar pucker, slide and x-displacement values typical of A-DNA. The structure shows highly ordered water structures, such as a double spine of water molecules against each side of the major groove, stabilizing the GC base pairs in an A-like conformation. The different hydration of GC and AT base pairs provides a physical basis for solvent-dependent facilitation of the A<-->B helix transition by GC base pairs. Crystal structures of CATGGGCCCATG and other A/B-DNA intermediates support a 'slide first, roll later' mechanism for the B-->A helix transition. In the distribution of helical parameters in protein-DNA crystal structures, GpG base steps show A-like properties, reflecting their innate predisposition for the A conformation.
    [Abstract] [Full Text] [Related] [New Search]