title: The structural organization of DNA packaged within the heads of T4 wild-type, isometric and giant bacteriophages.
abstract: We present electron microscopic and X-ray diffraction evidence concerning the structural organization of condensed DNA within a series of T4 bacteriophage with the following head morphologies: prolate (wild-type), isometric and giant (with greatly increased axial ratio). In all cases, the DNA helix segments are locally parallel and 27 A apart. For the giant particles, we show that the DNA forms a large coil whose axis is perpendicular to the axis of the phage tail. This evidence, combined with previous results from a series of isometric bacteriophages (Earnshaw and Harrison, 1977), leads to a model for the organization of condensed DNA that may apply to most dsDNA-containing bacteriophages.
mesh_terms: D003090:Coliphages / Q000648:ultrastructure*; D004279:DNA, Viral; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation; D014961:X-Ray Diffraction
chemical_list: D004279:DNA, Viral