Acetophenone reductase (APRD) from Geotrichum candidium NBRC 4597 was crystallized by the hanging-drop vapour-diffusion method using PEG 3350 as a precipitant. The crystal belonged to space group P6522, with unit-cell parameters a = b = 104.5, c = 273.7 Å, and diffracted to 2.6 Å resolution. Phasing using the single-wavelength anomalous diffraction method was successful. Model building and crystallographic refinement are in progress.
The antibody IgE plays a central role in allergic disease, functioning principally through two cell-surface receptors: Fc epsilon RI and CD23. Fc epsilon RI on mast cells and basophils mediates the immediate hypersensitivity response, whilst the interaction of IgE with CD23 on B cells regulates IgE production. Crystal structures of the lectin-like 'head' domain of CD23 alone and bound to a subfragment of IgE consisting of the dimer of C epsilon 3 and C epsilon 4 domains (Fc epsilon 3-4) have recently been determined, revealing flexibility in the IgE-binding site of CD23. Here, a new crystal form of the CD23-Fc epsilon 3-4 complex with different molecular-packing constraints is reported, which together with the earlier results demonstrates that conformational variability at the interface extends additionally to the IgE Fc and the quaternary structure of its domains.
Dragon grouper nervous necrosis virus (DGNNV), a member of the genus Betanodavirus, causes high mortality of larvae and juveniles of the grouper fish Epinephelus lanceolatus. Currently, there is no reported crystal structure of a fish nodavirus. The DGNNV virion capsid is derived from a single open reading frame that encodes a 338-amino-acid protein of approximately 37 kDa. The capsid protein of DGNNV was expressed to form virus-like particles (VLPs) in Escherichia coli. The VLP shape is T = 3 quasi-symmetric with a diameter of ∼38 nm in cryo-electron microscopy images and is highly similar to the native virion. In this report, crystals of DGNNV VLPs were grown to a size of 0.27 mm within two weeks by the hanging-drop vapour-diffusion method at 283 K and diffracted X-rays to ∼7.5 Å resolution. In-house X-ray diffraction data of the DGNNV VLP crystals showed that the crystals belonged to space group R32, with unit-cell parameters a = b = 353.00, c = 800.40 Å, α = β = 90, γ = 120°. 23 268 unique reflections were acquired with an overall Rmerge of 18.2% and a completeness of 93.2%. Self-rotation function maps confirmed the fivefold, threefold and twofold symmetries of the icosahedron of DGNNV VLPs.
The prokaryotic lysine-specific permease (LysP) belongs to the amino acid-polyamine-organocation (APC) transporter superfamily. In the cell, members of this family are responsible for the uptake and recycling of nutrients, for the maintenance of a constant internal ion concentration and for cell volume regulation. The detailed mechanism of substrate selectivity and transport of L-lysine by LysP is not understood. A high-resolution crystal structure would enormously facilitate such an understanding. To this end, LysP from Pseudomonas aeruginosa was recombinantly expressed in Escherichia coli and purified to near homogeneity by immobilized metal ion-affinity chromatography (IMAC) and size-exclusion chromatography (SEC). Hexagonal- and rod-shaped crystals were obtained in the presence of L-lysine and the L-lysine analogue L-4-thialysine by vapour diffusion and diffracted to 7.5 Å resolution. The diffraction data were indexed in space group P21, with unit-cell parameters a = 169.53, b = 169.53, c = 290.13 Å, γ = 120°.
The histidine-aspartate (HD) domain exerts phosphohydrolase activity on nucleotides and functions in nucleotide metabolism. Sequence analysis suggested that YpgQ from Bacillus subtilis contains the HD domain, but the structure and function of YpgQ remain to be revealed. The recombinant YpgQ protein was overexpressed in an Escherichia coli cell expression system and was purified to homogeneity by Ni-NTA affinity and anion-exchange chromatography. Crystals in space group P2₁ were obtained in PEG 600 solutions and diffracted X-rays to 2.3 Å resolution. Moreover, X-ray fluorescence scans on YpgQ crystals demonstrated the metal-binding ability of YpgQ.
The flavoenzyme fructosyl peptide oxidase (FPOX) catalyses the oxidative deglycation of fructosyl amino acids or fructosyl dipeptides to produce amino acids, glucosone and hydrogen peroxide. In this study, FPOX protein from Eupenicillium terrenum sp. (EtFPOX) was expressed in Escherichia coli and purified by Ni-affinity and gel-filtration chromatography. EtFPOX crystals were obtained using the sitting-drop vapour-diffusion method with polyethylene glycol 3350 as precipitant. X-ray diffraction data were collected to 1.90 Å resolution using a synchrotron-radiation source. The crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 65.6, b = 80.0, c = 83.4 Å, and contained one molecule in the asymmetric unit. The calculated Matthews coefficient and solvent content were 2.22 Å(3) Da(-1) and 44.62%, respectively.
Peptide release factor 1 (RF1) regulates the termination of translation in protein synthesis by recognizing the stop codons. The eukaryotic RF1s (eRF1s) from Arabidopsis thaliana and human have different stop-codon preferences even though they share high sequence similarity. Based on known RF1 structures, it has been suggested that the specificity depends on both the local structure and the domain arrangement, but the lack of a structure of Arabidopsis eRF1 hinders a detailed comparison. To reveal the mechanism of stop-codon recognition and compare it with that of human eRF1, one of the three Arabidopsis eRF1s, AteRF1-1, was studied and a preliminary X-ray crystallographic analysis is reported here. The protein was overexpressed in Escherichia coli and crystallized at room temperature using the vapour-diffusion method. Crystals were grown from 1.6 M lithium sulfate, 0.1 M Tris-HCl pH 8.0, 2%(v/v) PEG 400 and diffracted to 3.77 Å resolution. The data were processed in point group 622, with unit-cell parameters a = b = 136.6, c = 325.7 Å.
Abscisic acid (ABA) modulates many complicated developmental processes and responses to environmental stimuli. Recently, several (+)-ABA signalling mechanisms by the RCAR/PYR1/PYL family of proteins (PYLs) have been proposed. However, the mechanism of the recognition and binding of the unnatural ligand (-)-ABA by PYLs has not yet been elucidated. In the present study, the expression, purification and crystallization of PYL3 in complex with (-)-ABA are reported. Diffraction data were refined to 2.65 Å resolution for this complex in space group P65. These findings will help to explain the stereospecificity of PYLs for (-)-ABA and to explore the selective ABA agonists.
DNA double-strand breaks are highly detrimental genomic lesions that routinely arise in genomes. To protect the integrity of their genetic information, all organisms have evolved specialized DNA-repair mechanisms. Whirly proteins modulate DNA repair in plant chloroplasts and mitochondria by binding single-stranded DNA in a non-sequence-specific manner. Although most of the results showing the involvement of the Whirly proteins in DNA repair have been obtained in Arabidopsis thaliana, only the crystal structures of the potato Whirly proteins WHY1 and WHY2 have been reported to date. The present report of the crystal structures of the three Whirly proteins from A. thaliana (WHY1, WHY2 and WHY3) reveals that these structurally similar proteins assemble into tetramers. Furthermore, structural alignment with a potato WHY2–DNA complex reveals that the residues in these proteins are properly oriented to bind single-stranded DNA in a non-sequence-specific manner.
Peptidyl-tRNA is produced from the ribosome as a result of aborted translation. Peptidyl-tRNA hydrolase cleaves the ester bond between the peptide and the tRNA of peptidyl-tRNA molecules, to recycle tRNA for further rounds of protein synthesis. In this study, peptidyl-tRNA hydrolase from Thermus thermophilus HB8 (TthPth) was crystallized using 2-methyl-2,4-pentanediol as a precipitant. The crystals belonged to the orthorhombic space group P212121, with unit-cell parameters a = 47.45, b = 53.92, c = 58.67 Å, and diffracted X-rays to atomic resolution (beyond 1.0 Å resolution). The asymmetric unit is expected to contain one TthPth molecule, with a solvent content of 27.13% (VM = 1.69 Å3 Da−1). The structure is being solved by molecular replacement.
N(6)-methyladenosine (m6A) is a ubiquitous modification found in mammalian mRNA and long noncoding RNA. ALKBH5 is a member of the iron(II)- and 2-oxoglutarate-dependent AlkB oxygenase family and has been shown to catalyze the oxidative demethylation of N(6)-methyladenosine in RNA. The ALKBH5 protein was purified and crystallized using the hanging-drop vapour-diffusion method. The crystals diffracted to 2.4 Å resolution using synchrotron radiation. The crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 57.456, b = 83.406, c = 92.909 Å, α = β = γ = 90.00° and one molecule in the asymmetric unit.
Improving the specificity of α-cyclodextrin glucanotransferase is a significant issue in the field of α-cyclodextrin production. In this study, a constructed Y167H mutant α-cyclodextrin glucanotransferase with enhanced α-cyclodextrin specificity was successfully expressed and purified. Single crystals were grown using PEG 4000 as a precipitating agent by the hanging-drop vapour-diffusion method at 293 K. The crystals exhibited two kinds of morphology in different crystallization conditions. The crystals diffracted to at least 2.2 Å resolution (space group P2₁2₁2₁), with unit-cell parameters a=65.69, b=78.70, c=137.00 Å. Assuming the asymmetric cell to be occupied by a monomer of 75 kDa, the unit cell contains 43.77% solvent with a crystal volume per protein mass, VM, of 2.19 Å3 Da(-1).
Peptidylarginine deiminase (PAD) catalyzes the post-translational conversion of peptidylarginine to peptidylcitrulline in the presence of calcium ions. Among the five known human PAD isozymes (PAD1-4 and PAD6), PAD1 exhibits the broadest substrate specificity. Crystals of PAD1 obtained using polyethylene glycol 3350 as a precipitant diffracted to 3.70 Å resolution using synchrotron radiation. Two PAD1 molecules were contained in the asymmetric unit and the crystals belonged to space group P6(1), with unit-cell parameters a = b = 90.3, c = 372.3 Å. The solvent content was 58.2%.
Influenza virus is a major viral respiratory pathogen that causes yearly epidemics in temperate climates. The H3N2 subtype is one of the major causative agents of severe epidemics and plays a critical role in vaccine development. The neuraminidase (NA) inhibitors oseltamivir and zanamivir are two commercially available NA-targeted competitive antiviral drugs. However, their effectiveness has been compromised by the rapid emergence of resistance. Q136K is a novel mutation in NA which confers resistance to zanamivir. In this study, a Q136K mutant N2 protein was expressed in a baculovirus system and crystals were obtained. The crystal of N2 belonged to space group P2₁2₁2₁, with unit-cell parameters a = 109.5, b = 112.8, c = 165.2 Å. Data were collected to 2.4 Å resolution. Four monomers were found in the asymmetric unit. The Matthews coefficient and solvent content were calculated to be 3.0 ų Da⁻¹ and 59.0%, respectively.
Xyloglucanases (Xghs) are important enzymes involved in xyloglucan modification and degradation. Xanthomonas campestris pv. campestris (Xcc) is a phytopathogenic bacterium which produces a large number of glycosyl hydrolases (GH), but has only one family 74 GH (Xcc-Xgh). This enzyme was overexpressed in Escherichia coli, purified and crystallized. Diffraction data sets were collected for the native enzyme and its complex with glucose to maximum resolutions of 2.0 and 2.1 Å, respectively. The data were indexed in a hexagonal crystal system with unit-cell parameters a = b = 153.4, c = 84.9 Å. As indicated by molecular-replacement solution, the crystals belonged to space group P61.
DNA-dependent RNA polymerase (RNAP) synthesizes RNA complementary to the template DNA. During transcript elongation, RNAP often undergoes backward translocation (`backtracking') by dissociating the 3′ end of the nascent RNA transcript from the template DNA. While the backtracked state of RNAP is inactive in RNA elongation, it actively hydrolyses the RNA 3′ end to regenerate the active elongation complex. To study the structural basis of the backtracked state and its cleavage activity, two backtracked RNAP complexes were reconstituted by assembling Thermus thermophilus RNAP with designed nucleic acid scaffolds. The reconstituted backtracked complexes were active in the transcript-cleavage reaction. These complexes were crystallized and X-ray diffraction data sets were obtained at resolutions of 3.4 and 3.7 Å.
Long-term nonprogression during simian immunodeficiency virus (SIV) infection has been strongly associated with the major histocompatibility complex (MHC) class I allele Mamu-B*17. Here, a complex of rhesus macaque Mamu-B*17 with rhesus macaque β2-microglobulin (β2m) and an immunodominant peptide (SIVmac239 Env241-251; LRCNDTNYSGF; Env LF11) derived from the SIV Env protein was crystallized by the hanging-drop method using PEG 3350 as a precipitating agent. The crystals belonged to the primitive monoclinic space group P2, with unit-cell parameters a = 68.3, b = 45.0, c = 81.5 Å, β = 96.5°. Assuming the presence of one molecule in the asymmetric unit, the Matthews coefficient and solvent content were calculated to be 2.96 Å(3) Da(-1) and 58.5%, respectively.
Tannase catalyses the hydrolysis of the galloyl ester bond of tannins to release gallic acid. It belongs to the serine esterases and has wide applications in the food, feed, beverage, pharmaceutical and chemical industries. The tannase from Lactobacillus plantarum was cloned, expressed and purified. The protein was crystallized by the sitting-drop vapour-diffusion method with microseeding. The crystals belonged to space group P1, with unit-cell parameters a = 46.5, b = 62.8, c = 83.8 Å, α = 70.4, β = 86.0, γ = 79.4°. Although the enzyme exists mainly as a monomer in solution, it forms a dimer in the asymmetric unit of the crystal. The crystals diffracted to beyond 1.60 Å resolution using synchrotron radiation and a complete data set was collected to 1.65 Å resolution.
Wuhan nodavirus (WhNV), which is a new member of the Nodaviridae family, encodes a viral protein, B2, that suppresses RNA silencing and host-cell RNA interference (RNAi)-mediated immunity. Although Flock House virus (FHV), another member of the Nodaviridae family, also produces a B2 protein with a similar function, the primary sequences of the B2 proteins from WhNV and FHV have no similarity. To gain a better understanding of the structural details and the mechanism of suppression of RNA silencing by WhNV B2 and to compare it with FHV B2, recombinant WhNV B2 protein has been overexpressed in Escherichia coli, purified and crystallized at 291 K using PEG 4000 as a precipitant. A 2.8 Å resolution data set has been collected from a single crystal at 100 K. This crystal belonged to space group P2₁2₁2₁, with unit-cell parameters a=27.3, b=45.6, c=133.9 Å, α=β=γ=90°. Assuming the presence of two molecules in the asymmetric unit, the Matthews coefficient is 2.2 Å3 Da(-1).
Pseudomonas aeruginosa uses the type VI secretion system (T6SS) to inject effector proteins into rival cells in niche competition. Tse3, one of the effectors of T6SS, is delivered into the periplasm of recipient cells. Tse3 functions as a muramidase that degrades the β-1,4-linkage between N-acetylmuramic acid (MurNAc) and N-acetylglucosamine (GlcNAc) in peptidoglycan, thus leading to lysis of the recipient cells and providing a competitive advantage to the donor cells. Here, the preliminary crystallographic study of Tse3 is reported. A crystal of Tse3 diffracted to 1.5 Å resolution. It belonged to space group C121, with unit-cell parameters a = 166.99, b = 70.13, c = 41.94 Å, α = 90.00, β = 90.52, γ = 90.00° and one molecule per asymmetric unit.
