title: Crystallographic studies on E. coli Trp aporepressor.
abstract: Two crystal forms of Trp aporepressor, an inactive, unliganded form of Trp repressor have been obtained which are suitable for high resolution X-ray diffraction analysis. Trp aporepressor crystallizes in two forms: orthorhombic, P 2(1)2(1)2 and tetragonal P 4(1) (or P 4(3] which diffract to 1.8 A and 2.4 A, respectively. The orthorhombic crystals contain one monomer in the asymmetric unit, therefore the twofold axis relates two subunits of the dimer as in the case of the previously described Trp repressor (R. Schevitz et al., 1985, Nature, 317, 782-786) and Trp pseudorepressor (C. Lawson & P. B. Sigler, 1988, Nature, 333, 869-871). The tetragonal crystals have two dimers in the asymmetric unit and are nearly isomorphous with the tetragonal crystals of Trp repressor and Trp pseudorepressor grown under similar conditions but in the presence of an activator or inhibitor, respectively.
authors.affiliation: Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland.
authors.forename: A
authors.initials: A
authors.lastname: Joachimiak
authors.forename: R G
authors.initials: RG
authors.lastname: Zhang
mesh_terms: D001059:Apoproteins / Q000737:chemistry*; D001426:Bacterial Proteins; D004926:Escherichia coli / Q000032:analysis; D029968:Escherichia coli Proteins; D011487:Protein Conformation; D012097:Repressor Proteins / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D001059:Apoproteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; C027190:TRPR protein, E coli