CRYSTALLIZATION OF THE MS2 TRANSLATIONAL REPRESSOR ALONE AND COMPLEXED TO BROMOURIDINE

The coat protein from the MS2 bacteriophage plays a dual role by encap sidating viral RNA and also by binding RNA as a translational represso r. In order to study the isolated dimer in a conformation not influenc ed by capsid interactions, a mutant molecule was crystallized that is defective in capsid assembly but is an active repressor. The unassembl ed dimer crystallized in the space group P2(1)2(1)2 with a = 76.2, b = 55.7, and c = 28.4 Angstrom. In these crystals, monomers were related by twofold symmetry. When this dimer was co-crystallized with 5-bromo uridine, crystals formed in space group R3 with a = b = 155.9 Angstrom , c = 29.9 Angstrom, gamma = 120 degrees; the dimer was the asymmetric unit.