mutant D83G/F149S in complex with 5-phospho-alpha-D-ribose 1-diphosphate and Mn2+, to 2.25 A resolution. Protein backbone of mutant D83G/F149S shows no detectable differences to the wild-type enzyme, whereas 5-phospho-alpha-D-ribose 1-diphosphate bound to mutant D83G/F149S adopts an extended conformation that contrasts markedly with the S compact shape observed in complexes of the wild-type enzyme
mutant M47D, structurally very similar to wild-type (rms deviation of 0.7 A for most of equivalent C(alpha) atoms) but reduced buried surface area per subunit compared to wild-type homodimer, Aps47 protonated at pH 6, crystals of space group P2 with four molecules (two homodimers) per asymmetric unit and A2 pseudo-symmetry, unit cell parameters a=91.6 A, b=65.9 A, c=115.7 A, beta=107.4°, 45% (v/v) solvent content, hanging drop method: 1 microlitre protein solution (5 mg/ml) + 1 microlitre reservior solution (50 mM MES pH 6.0, 18% (v/v) PEG, 5% (v/v) glycerol), room temperature, 72 h
the crystal structure of the dimeric class III phosphoribosyltransferase. The active site of this enzyme is located within the flexible hinge region of its two-domain structure. The pyrophosphate moiety of phosphoribosylpyrophosphate is coordinated by a metal ion and is bound by two conserved loop regions within this hinge region. With the structure of AnPRT available, structural analysis of all enzymatic activities of the tryptophan biosynthesis pathway is complete, thereby connecting the evolution of its enzyme members to the general development of metabolic processes. Its structure reveals it to have the same fold, topology, active site location and type of association as class II nucleoside phosphorylases. At the level of sequences, this relationship is mirrored by 13 structurally invariant residues common to both enzyme families