Purification, crystallization and initial X-ray analysis of the head–tail connector of bacteriophage φ29

The head–tail connector of bacteriophage φ29, an oligomer of gene product 10 (gp10), was crystallized into various forms. The most useful of these were an orthorhombic P22121 form (unit-cell parameters a = 143.0, b = 157.0, c = 245.2 A), a monoclinic C2 form (a = 160.7, b = 143.6, c = 221.0 A, β = 97.8°) and another monoclinic C2 form (a = 177.0, b = 169.1, c = 185.2 A, β = 114.1°). Frozen crystals diffracted to about 3.2 A resolution. There is one connector per crystallographic asymmetric unit in each case. Rotation functions show the connector to be a dodecamer. Translation functions readily determined the position of the 12-fold axis in each unit cell. The structure is being determined by 12-fold electron-density averaging within each crystal and by averaging between the various crystal forms.