EXPRESSION, CRYSTALLIZATION AND PRELIMINARY-X-RAY DIFFRACTION STUDY OF FTSY, THE DOCKING PROTEIN OF THE SIGNAL RECOGNITION PARTICLE OF ESCHERICHIA-COLI

FtsY is the docking protein or SR alpha homologue in E. coli. It is in volved in targeting secretory proteins to the cytoplasmic membrane by interacting with the signal recognition particle, controlled by guanos ine 5'-triphosphate. Two different constructs have been used in crysta llization studies: the full-length protein and a truncated fragment wi th a his-tag at the C terminus. Only the second construct resulted in crystals suitable for x-ray diffraction. The crystals belong to the mo noclinic space group P2(1) with cell dimensions alpha = 32.20 Angstrom , b = 79.57 Angstrom, c = 59.21 Angstrom, and beta = 94.45, and contai n one molecule per asymmetric unit. At cryogenic temperatures the crys tals diffract to a resolution limit of 2.5 Angstrom by using a rotatin g anode, and beyond 1.8 Angstrom by using synchrotron radiation. (C) 1 997 Wiley-Liss, Inc.