Purification, crystallization and initial X-ray analysis of the head-tail connector of bacteriophage phi 29

The head-tail connector of bacteriophage phi 29, an oligomer of gene produc t 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 = 1 57.0, c = 245.2 Angstrom), a monoclinic C2 form (a = 160.7, b = 143.6, c = 221.0 Angstrom, beta = 97.8 degrees) and another monoclinic C2 form (a = 17 7.0, b = 169.1, c = 185.2 Angstrom, beta = 114.1 degrees). Frozen crystals diffracted to about 3.2 Angstrom resolution. There is one connector per cry stallographic asymmetric unit in each case. Rotation functions show the con nector to be a dodecamer. Translation functions readily determined the posi tion of the 12-fold axis in each unit cell. The structure is being determin ed by 12-fold electron-density averaging within each crystal and by averagi ng between the various crystal forms.