title: Crystallization and preliminary X-ray analysis of the hydroperoxidase I C-terminal domain from Escherichia coli.
abstract: Hydroperoxidases (HP) are normally large haem-containing bifunctional enzymes capable of acting as both catalases and peroxidases. The C-terminal domain of HPI from Escherichia coli (KatG), extending from residue Tyr422 to Leu726, was found to be resistant to trypsin proteolysis. The segment of katG encoding this domain was cloned and overexpressed to produce a haemless protein that is soluble even at concentrations above 30 mg ml(-1). This protein shows a 25% sequence identity with cytochrome c peroxidase (CCP) from Saccharomyces cerevisae, despite lacking the characteristic catalytic and iron-binding residues. Crystals from this protein were grown in 0.6 M sodium citrate buffered to pH 7.5 with HEPES by the hanging-drop vapour-diffusion method at 293 K. These crystals diffracted beyond 2.0 A resolution and belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 84.2, b = 98.7, c = 302.8 A. Three pseudo-origin peaks in the Patterson maps indicate an unusual packing compatible with the presence of three molecules in the crystal asymmetric unit and a solvent content of about 80% by volume.
authors.affiliation: Institut de Biología Molecular de Barcelona CSIC, Jordi-Girona 18-26, 08034 Barcelona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Carpena
authors.forename: Alba
authors.initials: A
authors.lastname: Guarné
authors.forename: Juan C
authors.initials: JC
authors.lastname: Ferrer
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Alzari
authors.forename: Ignacio
authors.initials: I
authors.lastname: Fita
authors.forename: Peter C
authors.initials: PC
authors.lastname: Loewen
mesh_terms: D002374:Catalase / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D017434:Protein Structure, Tertiary
chemical_list: D029968:Escherichia coli Proteins; D002374:Catalase; C051253:katG protein, E coli