Purification, crystallization and initial X-ray analysis of the head-tail connector of bacteriophage phi29

The head-tail connector of bacteriophage phi29, an oligomer of gene product 10 (gp10), was crystallized into various forms. The most useful of these were an orthorhombic P22(1)2(1) 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, beta = 97.8 degrees ) and another monoclinic C2 form (a = 177.0, b = 169.1, c = 185.2 A, beta = 114.1 degrees ). 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.