Purification, crystallization and preliminary crystallographic analysis of RecA superfamily ATPase PH0284 from Pyrococcus horikoshii OT3

RecA superfamily ATPase PH0284 from P. horikoshii OT3 was overexpressed, purified, crystallized and cocrystallized with ATP. Both crystal forms belong to the trigonal space group P3221 and diffract X-rays to 2.0 and 2.3 Å resolution, respectively

Purification, crystallization and preliminary crystallographic analysis of archaeal 6-pyruvoyl tetrahydrobiopterin synthase homologue PH0634 from Pyrococcus horikoshii OT3

An archaeal 6-pyruvoyl tetrahydrobiopterin synthase homologue from P. horikoshii OT3 was overexpressed as native and selenomethionine-substituted protein, purified and crystallized. The native and selenomethionine-derivative crystals are isomorphous and diffract X-rays to 2.1 and 2.9 Å resolution, respectively

Modulated structures of Cs2HgCl4Cs_2 HgCl_4 : the 5aa superstructure at 185 K and the 3cc superstructure at 176 K

Crystalline dicaesium mercury tetrachloride (Cs2HgCl4) is isomorphous with beta-K2SO4 (space group Pnma, Z = 4) in its normal phase at room temperature. On cooling a sequence of incommensurate and commensurate superstructures occurs, below T = 221 K with modulations parallel to a*, and below 184 K with modulations along c*. The commensurately modulated structures at T = 185 K with q = 1/5a* and at T= 176 K with q = 1/3c* were determined using X-ray scattering with synchrotron radiation. The structure at T = 185 K has superspace group Pnma(alpha, 0, 0)0ss with alpha = 0.2. Lattice parameters were determined as a = 5 x 9.7729 (1), b = 7.5276 (4) and c = 13.3727 (7) Angstrom. Structure refinements converged to R = 0.050 (R = 0.042 for 939 main reflections and R = 0.220 for 307 satellites) for the section t = 0.05 of superspace. The fivefold supercell has space group Pn2(1)a. The structure at T = 176 K has superspace group Pnma(0, 0, gamma)0s0 with gamma = 1/3. Lattice parameters were determined as a = 9.789 (3), b = 7.541 (3) and c = 3 x 13.418 (4) Angstrom. Structure refinements converged to R = 0.067 (R = 0.048 for 2130 main reflections, and R = 0.135 for 2382 satellite reflections) for the section t = 0. The threefold supercell has space group P112(1)/a. It is shown that the structures of both low-temperature phases can be characterized as different superstructures of the periodic room-temperature structure. The superstructure of the 5a-modulated phase is analysed in terms of displacements of the Cs atoms, and rotations and distortions of HgCl4 tetrahedral groups In the 3c-modulated phase the distortions of the tetrahedra are relaxed, but they are replaced by translations of the tetrahedral groups in addition to rotations

Purification, crystallization and preliminary crystallographic analysis of the biotin–protein ligase from Pyrococcus horikoshii OT3

The biotin–protein ligase from P. horikoshii OT3 was overexpressed, purified, crystallized and cocrystallized with biotin, ADP and biotinyl-5′-AMP. The crystals belong to space group P21 and diffract to beyond 1.6 Å resolution

Structural basis for the phase transitions of Cs2HgCl4Cs_2HgCl_4

The a 0 × b 0 × 2c 0 twofold superstructure of dicaesium mercury tetrachloride, Cs2HgCl4, at T = 120 K has been determined by single-crystal X-ray diffraction using synchrotron radiation. Lattice parameters were found as a = 9.7105 (2), b = 7.4691 (1), c = 26.8992 (4) Å, and β = 90.368 (1)° with the supercell space group P21/c. Refinements on 1828 observed unique reflections converged to R = 0.053 (wR = 0.057) using anisotropic temperature factors for all atoms. This phase is the stable phase of Cs2HgCl4 below 163 K. A quantitative comparison is made of the distortions of the 2c 0 superstructure with the undistorted phase that is stable at room temperature, and with the 3c 0 and 5a 0 superstructures that are stable at temperatures between 163 K and room temperature. The principal difference between the 2c 0 superstructure and all other phases of Cs2HgCl4 is that the Cs cations are displaced away from the centers of their coordination polyhedra in the 2c 0 superstructure. The structural basis for the driving force of the series of phase transitions in this compound is found in the variations of the environments of Cs atoms and in the variations of the distortions of the HgCl4 tetrahedra.</jats:p

Crystallization and preliminary X-ray crystallographic studies of the biotin carboxyl carrier protein and biotin protein ligase complex from Pyrococcus horikoshii OT3

A truncated form of biotin carboxyl carrier protein containing the C-terminal half fragment (BCCPΔN76) and the biotin protein ligase (BPL) with the mutation R48A (BPL*) or the double mutation R48A K111A (BPL**) were successfully cocrystallized in the presence of ATP and biotin. The BPL*–BCCPΔN76 and BPL**–BCCPΔN76 crystals belong to space group P21 and diffract X-rays to 2.7 and 2.0 Å resolution, respectively