STRUCTURE OF OLIGOMERIC BETA-B2-CRYSTALLIN - AN APPLICATION OF THE T2 TRANSLATION FUNCTION TO AN ASYMMETRIC UNIT CONTAINING 2 DIMERS

The molecular structure of the main subunit of the beta-crystallins, components of the vertebrate eye lens, has recently been solved by molecular replacement at 2.1 angstrom resolution [Bax, Lapatto, Nalini, Driessen, Lindley, Mahadevan, Blundell & Slingsby (1990). Nature (London), 347, 776-780]. The protein, beta-B2, is a dimer in solution, but a tetramer in the crystal with one subunit in the asymmetric unit of space group I222. Using the crystallographic dimer from this I-centred form the structure of a C222 crystal form of the beta-B2 protein with four subunits in the asymmetric unit has now been solved by molecular replacement at 3.3 angstrom. The solution involved the use of a new translation function for non-crystallographic symmetry, based on the T2 function of Crowther & Blow [Acta Cryst. (1967), 23, 544-548].