Crystallization of the major coat protein of PRD1, a bacteriophage with an internal membrane

The major multimeric coat protein, P3, of the bacterial virus PRD1 has been crystallized by vapor diffusion from polyethylene glycol 4000. The PRD1-P3 crystals belong to the orthorhombic space group P2(1)2(1)2(1) with unit cell dimensions a = 121.6 A, b = 123.2 A, c = 128.6 A and diffract to 3.0 A resolution. Density measurements show that there is one trimer (3 x 43.1 kDa) per asymmetric unit and a high solvent content of 67%. A self-rotation function calculation shows a pronounced peak indicating a non-crystallographic threefold axis. This indicates that the major viral capsomer is a trimer and allows the viral T-number to be postulated.