Preliminary X-ray crystallographic studies of yeast Hsp40 Ydj1 complexed with its peptide substrate

The mechanism by which Hsp40 functions as a molecular chaperone, recognizing and binding non-native polypeptides, is not understood. To investigate the mechanism, the yeast type I Hsp40 protein Ydj1 C-terminal peptide-binding fragment has been crystallized complexed with its peptide substrate. The crystals diffract to 2.70 A using a synchrotron X-ray source and belong to space group P3(2)21 or P3(1)21, with unit-cell parameters a = b = 55.21, c = 161.87 A, alpha = beta = 90, gamma = 120 degrees. There is one Ydj1 peptide-binding fragment and one peptide substrate in the asymmetric unit, which corresponds to a solvent content of approximately 42%. Structure determination by MAD methods is under way.