Crystals of the human Plk1 Polo-box domain in complex with a Cdc25C target peptide in an unphosphorylated and a phosphorylated state have been obtained in orthorhombic and monoclinic forms that diffract to 2.1 and 2.85 Å, respectively, using synchrotron radiation.
Polo-like kinase (Plk1) is crucial for cell-cycle progression via mitosis. Members of the Polo-like kinase family are characterized by the presence of a C-terminal domain termed the Polo-box domain (PBD) in addition to the N-terminal kinase domain. The PBD of Plk1 was cloned and overexpressed in Escherichia coli. Crystallization experiments of the protein in complex with an unphosphorylated and a phosphorylated target peptide from Cdc25C yield crystals suitable for X-ray diffraction analysis. Crystals of the PBD in complex with the phosphorylated peptide belong to the orthorhombic space group P212121, with unit-cell parameters a = 38.23, b = 67.35, c = 88.25 Å, α = γ = β = 90°, and contain one molecule per asymmetric unit. Crystals of the PBD in complex with the unphosphorylated peptide belong to the monoclinic space group P21, with unit-cell parameters a = 40.18, b = 49.17, c = 56.23 Å, α = γ = 90, β = 109.48°, and contain one molecule per asymmetric unit. The crystals diffracted to resolution limits of 2.1 and 2.85 Å using synchrotron radiation at the European Synchrotron Radiation Facility (ESRF) and the Swiss Light Source (SLS), respectively.
Polo-like kinase; Polo-box domain; Cdc25C
The X-ray crystallographic structure of a dimer variant of fructose-1,6-bisphosphate aldolase demonstrates a stable oligomer that mirrors half of the native tetramer. The presence of product demonstrates that this is an active form.
Fructose-1,6-bisphosphate aldolase (aldolase) is an essential enzyme in glycolysis and gluconeogenesis. In addition to this primary function, aldolase is also known to bind to a variety of other proteins, a property that may allow it to perform ‘moonlighting’ roles in the cell. Although monomeric and dimeric aldolases possess full catalytic activity, the enzyme occurs as an unusually stable tetramer, suggesting a possible link between the oligomeric state and these noncatalytic cellular roles. Here, the first high-resolution X-ray crystal structure of rabbit muscle D128V aldolase, a dimeric form of aldolase mimicking the clinically important D128G mutation in humans associated with hemolytic anemia, is presented. The structure of the dimer was determined to 1.7 Å resolution with the product DHAP bound in the active site. The turnover of substrate to produce the product ligand demonstrates the retention of catalytic activity by the dimeric aldolase. The D128V mutation causes aldolase to lose intermolecular contacts with the neighboring subunit at one of the two interfaces of the tetramer. The tertiary structure of the dimer does not significantly differ from the structure of half of the tetramer. Analytical ultracentrifugation confirms the occurrence of the enzyme as a dimer in solution. The highly stable structure of aldolase with an independent active site is consistent with a model in which aldolase has evolved as a multimeric scaffold to perform other noncatalytic functions.
dimeric aldolase; hemolytic anemia; D128V; oligomerization
At room temperature, the m-Nitrophenol (m-NPH) appears in two polymorphic structures: orthorhombic and monoclinic forms. In the present work, we shall focus on the monoclinic form of this compound which has a centrosymmetric structure with the space group P21/n. The molecular dipole moment has been estimated experimentally. High resolution single crystal diffraction experiment was performed at low temperature with MoKα radiation. The crystal structure was refined using the multipolar model of Hansen and Coppens (1978). The molecular electron charge density distribution is described accurately. The study reveals the nature of inter-molecular interactions including charge transfer and hydrogen bonds. In this crystal, hydrogen bonds of moderate strength occur between the hydroxyl group and the O atom in the nitro one.
Electron charge density; M-Nitrophenol; XD program; nonlinear optical compound (NLO)
An 8 kDa proteolytic fragment of the A. majus RADIALIS protein was crystallized and X-ray data were collected to 2 Å resolution.
Crystals of the RADIALIS protein from Antirrhinum majus were grown by vapour diffusion after limited proteolysis. Mass spectrometry indicated that an 8 kDa fragment had been crystallized corresponding to the predicted MYB DNA-binding domain. X-ray data collected at room temperature were consistent with tetragonal symmetry, whereas data collected at 100 K using crystals cryoprotected by supplementing the mother liquor with ethylene glycol conformed to orthorhombic symmetry. It was subsequently shown that crystals soaked in cryoprotectants that were ‘osmolality-matched’ to the mother liquor retained tetragonal symmetry. Using these crystals, X-ray data were collected in-house to a maximum resolution of 2 Å.
RADIALIS; limited proteolysis; osmolality
Streak-seeding markedly improved the stability, crystal-growth rate and diffraction quality of dilated-cardiomyopathy-associated mutant metavinculin crystals.
Metavinculin is an alternatively spliced isoform of vinculin that has a 68-residue insert in its tail domain (1134 total residues) and is exclusively expressed in cardiac and smooth muscle tissue, where it plays important roles in myocyte adhesion complexes. Mutations in the metavinculin-specific insert are associated with dilated cardiomyopathy (DCM) in man. Crystals of a DCM-associated mutant of full-length selenomethionine-labeled metavinculin grown by hanging-drop vapor diffusion diffracted poorly and were highly sensitive to radiation, preventing the collection of a complete X-ray diffraction data set at the highest possible resolution. Streak-seeding markedly improved the stability, crystal-growth rate and diffraction quality of DCM-associated mutant metavinculin crystals, allowing complete data collection to 3.9 Å resolution. These crystals belonged to space group P43212, with two molecules in the asymmetric unit and unit-cell parameters a = b = 170, c = 211 Å, α = β = γ = 90°.
Recombinant human CLEC-2 was crystallized in the orthorhombic space group P212121 and X-ray diffraction data were collected to 2.0 Å.
The human C-type lectin-like protein CLEC-2 has recently been shown to be expressed on the surface of platelets and to function as a receptor for the snake-venom protein rhodocytin. The C-type lectin-like domain (CTLD) of CLEC-2 was expressed in Escherichia coli, refolded and purified. Crystals of this recombinant CLEC-2 were grown by sitting-drop vapour diffusion using polyethylene glycol (PEG) 6000 as a precipitant. After optimization, crystals were grown which diffracted to 2.0 Å using in-house radiation (λ = 1.5418 Å). These crystals belonged to the orthorhombic space group P212121, with unit-cell parameters a = 35.407, b = 55.143, c = 56.078 Å. The presence of one molecule per asymmetric unit is consistent with a crystal volume per unit weight (V
M) of 1.82 Å3 Da−1 and a solvent content of 32.6%. These results suggest that crystals producing diffraction of this quality will be suitable for the structural determination of human CLEC-2.
CLEC-2; CLEC1B; rhodocytin; aggretin; C-type lectins; platelets; thrombosis
The phase-selective crystallization of acetaminophen (ACM) using insoluble polymers as heteronuclei was investigated in a combined experimental and computational effort to elucidate the mechanism of polymer-induced heteronucleation (PIHn). ACM heteronucleates from supersaturated aqueous solution in its most thermodynamically stable monoclinic form on poly(n-butyl methacrylate), whereas the metastable orthorhombic form is observed on poly(methyl methacrylate). When ACM crystals were grown through vapor deposition, only the monoclinic polymorph was observed on each polymer. Each crystallization condition leads to a unique powder X-ray diffraction pattern with the major preferred orientation corresponding to the crystallographic faces in which these crystal phases nucleate from surfaces of the polymers. The molecular recognition events leading to these outcomes are elucidated with the aid of computed polymer-crystal binding energies using docking simulations. This investigation illuminates the mechanism by which phase-selection occurs during the crystallization of ACM using polymers as heteronuclei paving the way for the improvement of methods for polymorph selection and discovery based on heterogeneous nucleation promoters.
crystal polymorphism; X-ray diffractometry; preferred orientation; molecular dynamics; binding energy
Crystallization of and preliminary crystallographic studies on an active-site mutant of pro-Tk-subtilisin from the hyperthermophilic archaeon T. kodakaraensis were performed.
Crystallization of and preliminary crystallographic studies on an active-site mutant of pro-Tk-subtilisin from the hyperthermophilic archaeon Thermococcus kodakaraensis were performed. The crystal was grown at 277 K by the sitting-drop vapour-diffusion method. Native X-ray diffraction data were collected to 2.3 Å resolution using synchrotron radiation from station BL41XU at SPring-8. The crystal belongs to the orthorhombic space group I222, with unit-cell parameters a = 92.69, b = 121.78, c = 77.53 Å. Assuming the presence of one molecule per asymmetric unit, the Matthews coefficient V
M was calculated to be 2.6 Å3 Da−1 and the solvent content was 53.1%.
pro-Tk-subtilisin; Thermococcus kodakaraensis
ϕ29 bacteriophage scaffolding protein (gp7) has been overproduced in E. coli, purified, crystallized and characterized by X-ray diffraction. Two distinct crystal forms were obtained and a diffraction data set was collected to 1.8 Å resolution.
The Bacillus subtilis bacteriophage ϕ29 scaffolding protein (gp7) has been crystallized by the hanging-drop vapour-diffusion method at 293 K. Two new distinct crystal forms that both differed from a previously crystallized and solved scaffolding protein were grown under the same conditions. Form I belongs to the primitive tetragonal space group P41212, with unit-cell parameters a = b = 77.13, c = 37.12 Å. Form II crystals exhibit an orthorhombic crystal form, with space group C222 and unit-cell parameters a = 107.50, b = 107. 80, c = 37.34 Å. Complete data sets have been collected to 1.78 and 1.80 Å for forms I and II, respectively, at 100 K using Cu Kα X-rays from a rotating-anode generator. Calculation of a V
M value of 2.46 Å3 Da−1 for form I suggests the presence of one molecule in the asymmetric unit, corresponding to a solvent content of 50.90%, whereas form II has a V
M of 4.80 Å3 Da−1 with a solvent content of 48.76% and two molecules in the asymmetric unit. The structures of both crystal forms are being determined by the molecular-replacement method using the coordinates of the published crystal structure of gp7.
scaffolding protein; bacteriophage ϕ29
Full-length Mos1 transposase has been crystallized in a complex with inverted-repeat DNA. Crystals diffract to 3.25 Å resolution and display noncrystallographic twofold symmetry.
A complex formed between Mos1 transposase and its inverted-repeat DNA has been crystallized. The crystals diffract to 3.25 Å resolution and exhibit monoclinic (P21) symmetry, with unit-cell parameters a = 120.8, b = 85.1, c = 131.6 Å, β = 99.3°. The X-ray diffraction data display noncrystallographic twofold symmetry and characteristic dsDNA diffraction at ∼3.3 Å. Biochemical analyses confirmed the presence of DNA and full-length protein in the crystals. The relationship between the axis of noncrystallographic symmetry, the unit-cell axes and the DNA diffraction pattern are discussed. The data are consistent with the previously proposed model of the paired-ends complex containing a dimer of the transposase.
Mos1 transposase; inverted-repeat DNA
The flavin-dependent enzyme FerB from P. denitrificans has been purified and both native and SeMet-substituted FerB have been crystallized. The two variants crystallized in two different crystallographic forms belonging to the monoclinic space group P21 and the orthorhombic space group P21212, respectively. X-ray diffraction data were collected to 1.75 Å resolution for both forms.
The flavin-dependent enzyme FerB from Paracoccus denitrificans reduces a broad range of compounds, including ferric complexes, chromate and most notably quinones, at the expense of the reduced nicotinamide adenine dinucleotide cofactors NADH or NADPH. Recombinant unmodified and SeMet-substituted FerB were crystallized under similar conditions by the hanging-drop vapour-diffusion method with microseeding using PEG 4000 as the precipitant. FerB crystallized in several different crystal forms, some of which diffracted to approximately 1.8 Å resolution. The crystals of native FerB belonged to space group P21, with unit-cell parameters a = 61.6, b = 110.1, c = 65.2 Å, β = 118.2° and four protein molecules in the asymmetric unit, whilst the SeMet-substituted form crystallized in space group P21212, with unit-cell parameters a = 61.2, b = 89.2, c = 71.5 Å and two protein molecules in the asymmetric unit. Structure determination by the three-wavelength MAD/MRSAD method is now in progress.
flavoenzymes; quinone reductases; Paracoccus denitrificans
Crystals of NovN, an O-carbamoyltransferase from S. spheroides, were obtained in monoclinic and orthorhombic forms and native X-ray data were recorded to a maximum of 2.3 Å resolution.
Crystals of recombinant NovN, an O-carbamoyltransferase from Streptomyces spheroides, were grown by vapour diffusion. The protein crystallized in two different crystal forms. Crystal form I belonged to space group C2 and native data were collected to 2.9 Å resolution in-house. Crystal form II had I-centred orthorhombic symmetry and native data were recorded to a resolution of 2.3 Å at a synchrotron. NovN catalyses the final step in the biosynthesis of the aminocoumarin antibiotic novobiocin that targets the essential bacterial enzyme DNA gyrase.
NovN; O-carbamoyltransferases; Streptomyces; novobiocin; antibiotic biosynthesis
Crystals of the helicase domain from a tomato mosaic virus replication protein obtained using the hanging-drop vapour-diffusion method at 285 K diffracted X-rays to 2.05 Å resolution. They belonged to the orthorhombic space group P212121, with unit-cell parameters a = 85.8, b = 128.3, c = 40.7 Å.
Tomato mosaic virus belongs to the genus Tobamovirus in the alphavirus-like superfamily of positive-strand RNA viruses. The alphavirus-like superfamily includes many plant and animal viruses of agronomical and clinical importance. These viruses encode replication-associated proteins that contain a putative superfamily 1 helicase domain. No three-dimensional structures for this domain have been determined to date. Here, the crystallization and preliminary X-ray diffraction analysis of the 130K helicase domain are reported. Diffraction data were collected and processed to 2.05 and 1.75 Å resolution from native and selenomethionine-labelled crystals, respectively. The crystals belonged to the orthorhombic space group P212121, with unit-cell parameters a = 85.8, b = 128.3, c = 40.7 Å.
tomato mosaic virus; replicase protein; helicase domain
The enzyme cgHle from C. glutamicum, which has acetyl ester hydrolase activity, was crystallized in four different crystal forms. X-ray diffraction data have been collected to a resolution of 1.2 Å.
CgHle is an enzyme that is encoded by gene cg0961 from Corynebacterium glutamicum. The physiological function of cgHle is so far unclear. Bioinformatic annotations based on sequence homology indicated that cgHle may be an acetyl-CoA:homoserine acetyl transferase and as such may be involved in methionine biosynthesis, but recent evidence has shown that it is an esterase that catalyzes the hydrolysis of acetyl esters. Here, the crystallization of cgHle in two orthorhombic crystal forms, a trigonal crystal form and a monoclinic crystal form is described. The trigonal crystals have a solvent content of 83.7%, which is one of the highest solvent contents ever found for protein crystals. One of the orthorhombic crystals diffracted X-rays to at least 1.2 Å resolution.
CgHle; Corynebacterium glutamicum; homoserine acetyltransferases
Streptococcus pneumoniae is the major cause of community-acquired pneumonia and is also associated with bronchitis, meningitis, otitis and sinusitis. The emergence and increasing prevalence of resistance to penicillin and other antibiotics has led to interest in other anti-pneumonococcal drugs such as quinolones that target the enzymes DNA gyrase and topoisomerase IV. During crystallization and in the avenues to finding a method to determine phases for the structure of the ParC55 breakage-reunion domain of topoisomerase IV from Streptococcus pneumoniae, obstacles were faced at each stage of the process. These problems included: majority of the crystals being twinned, either non-diffracting or exhibiting a high mosaic spread. The crystals, which were grown under conditions that favoured diffraction, were difficult to flash-freeze without loosing diffraction. The initial structure solution by molecular replacement failed and the approach proved to be unviable due to the complexity of the problem. In the end the successful structure solution required an in-depth data analysis and a very detailed molecular replacement search.
Crystal anti-twinning agents have been tested and two different methods of flash freezing have been compared. The fragility of the crystals did not allow the usual method of transferring the crystals into the heavy atom solution. Consequently, it was necessary to co-crystallize in the presence of the heavy atom compound. The multiple isomorphous replacement approach was unsuccessful because the 7 cysteine mutants which were engineered could not be successfully derivatized. Ultimately, molecular replacement was used to solve the structure by sorting through a large number of solutions in space group P1 using CNS.
The main objective of this paper is to describe the obstacles which were faced and overcome in order to acquire data sets on such difficult crystals and determine phases for successful structure solution.
Three data sets have been collected on endothiapepsin complexed with the gem-diol inhibitor PD-135,040: a high-resolution synchrotron X-ray data set, a room-temperature X-ray data set and a neutron diffraction data set. Until recently, it has been impossible to grow large protein crystals of endothiapepsin with any gem-diol inhibitor that are suitable for neutron diffraction.
Endothiapepsin has been cocrystallized with the gem-diol inhibitor PD-135,040 in a low solvent-content (39%) unit cell, which is unprecedented for this enzyme–inhibitor complex and enables ultrahigh-resolution (1.0 Å) X-ray diffraction data to be collected. This atomic resolution X-ray data set will be used to deduce the protonation states of the catalytic aspartate residues. A room-temperature neutron data set has also been collected for joint refinement with a room-temperature X-ray data set in order to locate the H/D atoms at the active site.
endothiapepsin; gem-diol inhibitors; neutron diffraction
The title compound, C40H64O12, crystallizes in a pseudomerohedrally twinned primitive monoclinic cell with similar contributions of the two twin components. There are two symmetry-independent half-molecules of nonactin in the asymmetric unit. Each molecule has a pseudo-S
4 symmetry and resides on a crystallographic twofold axis; the axes pass through the molecular center of mass and are perpendicular to the plane of the macrocycle. The literature description of the room-temperature structure of nonactin as an order–disorder structure in an orthorhombic unit cell is corrected. We report a low-temperature high-precision ordered structure of ‘free’ nonactin that allowed for the first time precise determination of its bond distances and angles. It possesses an unfolded and more planar geometry than its complexes with encapsulated Na+, K+, Cs+, Ca2+ or NH4
+ cations that exhibit more isometric overall conformations.
A novel cardiotoxin-like basic protein from Naja naja atra was crystallized and diffraction data were collected to 2.35 Å resolution.
A novel cardiotoxin-like basic protein was isolated from the venom of the Chinese cobra (Naja naja atra) from the south of Anhui in China. The protein inhibits the expression of vascular endothelial growth factor and basic fibroblast growth factor in human lung cancer cell line H1299 and induces the haemolysis of rabbit erythrocytes under low-lecithin conditions. After a two-step chromatographic purification, the resultant 7 kDa protein was crystallized by the hanging-drop vapour-diffusion method at room temperature. A complete data set was collected to 2.35 Å resolution using an in-house X-ray diffraction system. The crystal belongs to space group P41212, with unit-cell parameters a = b = 43.2, c = 147.9 Å. There are two molecules in the crystallographic asymmetric unit.
snake venoms; cardiotoxin-like basic protein; vascular endothelial growth factor; basic fibroblast growth factor; neurotoxins; toxicity; haemolytic activity
Hepatitis B virus capsids have significant potential as carriers for immunogenic peptides. The crystal structure of the T = 4 particle of hepatitis B core protein containing an N-terminal extension reveals that the fusion peptide is exposed on the exterior of the particle.
Hepatitis B core (HBc) particles have been extensively exploited as carriers for foreign immunological epitopes in the development of multicomponent vaccines and diagnostic reagents. Crystals of the T = 4 HBc particle were grown in PEG 20 000, ammonium sulfate and various types of alcohols. A temperature jump from 277 or 283 to 290 K was found to enhance crystal growth. A crystal grown using MPD as a cryoprotectant diffracted X-rays to 7.7 Å resolution and data were collected to 99.6% completeness at 8.9 Å. The crystal belongs to space group P212121, with unit-cell parameters a = 352.3, b = 465.5, c = 645.0 Å. The electron-density map reveals a protrusion that is consistent with the N-terminus extending out from the surface of the capsid. The structure presented here supports the idea that N-terminal insertions can be exploited in the development of diagnostic reagents, multicomponent vaccines and delivery vehicles into mammalian cells.
hepatitis B core particles; cryoprotectant; temperature jump; N-terminal fusion
The crystallization and preliminary X-ray diffraction analysis of sarcosine dimethylglycine methyltransferase from H. halochoris is reported.
Sarcosine dimethylglycine methyltransferase (EC 188.8.131.52) is an enzyme from the extremely halophilic anaerobic bacterium Halorhodospira halochoris. This enzyme catalyzes the twofold methylation of sarcosine to betaine, with S-adenosylmethionine (AdoMet) as the methyl-group donor. This study presents the crystallization and preliminary X-ray analysis of recombinant sarcosine dimethylglycine methyltransferase produced in Escherichia coli. Mass spectroscopy was used to determine the purity and homogeneity of the enzyme material. Two different crystal forms, which initially appeared to be hexagonal and tetragonal, were obtained. However, on analyzing the diffraction data it was discovered that both crystal forms were pseudo-merohedrally twinned. The true crystal systems were monoclinic and orthorhombic. The monoclinic crystal diffracted to a maximum of 2.15 Å resolution and the orthorhombic crystal diffracted to 1.8 Å resolution.
sarcosine dimethylglycine methyltransferase; Halorhodospira halochoris; twinning
Crystals of the human immunodeficiency virus 1 subtype C protease complexed with indinavir and nelfinavir have been grown in the monoclinic space group P21 and shown to diffract X-rays to 2.3 Å resolution.
Crystals of the human immunodeficiency virus 1 (HIV-1) subtype C protease (PR) complexed with the clinically used inhibitors indinavir (IDV) and nelfinavir (NFV) have been grown in the monoclinic space group P21, with mean unit-cell parameters a = 46.7 (±0.1), b = 59.8 (±0.3), c = 87.0 (±0.4) Å, β = 95.2 (±0.5)°. The crystals of both complexes have been shown to diffract X-rays to 2.3 Å resolution. The diffraction data for the subtype C PR complexes with IDV and NFV were subsequently processed and reduced, with overall R
sym values of 8.4 and 11.4%, respectively. Based on the unit-cell volumes, molecular-replacement results and packing considerations, there are two protease homodimers per crystallographic asymmetric unit in each of the complexes. The data were initially phased using a model based on the crystal structure of HIV-1 subtype B PR; the structures have been determined and further refinement and analysis are in progress. These structures and subsequent studies with other inhibitors will greatly aid in correlating the amino-acid variation between the different HIV PRs and understanding their differential sensitivity and resistance to current drug therapy.
HIV-1; subtype C protease; indinavir; nelfinavir
The preparation and successful crystallization of the Grb7 SH2 domain in complex with the specific cyclic peptide inhibitor G7-18NATE are reported. This structure is anticipated to reveal the basis of the binding affinity and specificity and to assist with the development of second-generation inhibitors of Grb7, which is involved in cancer progression.
Grb7 is an adapter protein that is involved in signalling pathways that mediate eukaryotic cell proliferation and migration. Its overexpression in several cancer types has implicated it in cancer progression and led to the development of the G7-18NATE cyclic peptide inhibitor. Here, the preparation of crystals of G7-18NATE in complex with its Grb7 SH2 domain target is reported. Crystals of the complex were grown by the hanging-drop vapour-diffusion method using PEG 3350 as the precipitant at room temperature. X-ray diffraction data were collected from crystals to 2.4 Å resolution using synchrotron X-ray radiation at 100 K. The diffraction was consistent with space group P21, with unit-cell parameters a = 52.7, b = 79.1, c = 54.7 Å, α = γ = 90.0, β = 104.4°. The structure of the G7-18NATE peptide in complex with its target will facilitate the rational development of Grb7-targeted cancer therapeutics.
Grb7; SH2 domains; inhibitors; G7-18NATE
Parakeet (Psittacula krameri) haemoglobin has been purified and crystallized under low salt buffered conditions. Preliminary analysis of the crystal that belonged to monoclinic system (C2) is reported.
Birds often show efficient oxygen management in order to meet the special demands of their metabolism. However, the structural studies of avian haemoglobins (Hbs) are inadequate for complete understanding of the mechanism involved. Towards this end, purification, crystallization and preliminary X-ray diffraction studies have been carried out for parakeet Hb. Parakeet Hb was crystallized as the met form in low-salt buffered conditions after extracting haemoglobin from crude blood by microcentrifugation and purifying the sample by column chromatography. Good-quality crystals were grown from 10% PEG 3350 and a crystal diffracted to about 2.8 Å resolution. Preliminary diffraction data showed that the Hb crystal belonged to the monoclinic system (space group C2), with unit-cell parameters a = 110.68, b = 64.27, c = 56.40 Å, β = 109.35°. Matthews volume analysis indicated that the crystals contained a half-tetramer in the asymmetric unit.
avian haemoglobin; Psittacula krameri
The Microcapillary Protein Crystallization System (MPCS) is a new protein-crystallization technology used to generate nanolitre-sized crystallization experiments for crystal screening and optimization. Using the MPCS, diffraction-ready crystals were grown in the plastic MPCS CrystalCard and were used to solve the structure of methionine-R-sulfoxide reductase.
The Microcapillary Protein Crystallization System (MPCS) embodies a new semi-automated plug-based crystallization technology which enables nanolitre-volume screening of crystallization conditions in a plasticware format that allows crystals to be easily removed for traditional cryoprotection and X-ray diffraction data collection. Protein crystals grown in these plastic devices can be directly subjected to in situ X-ray diffraction studies. The MPCS integrates the formulation of crystallization cocktails with the preparation of the crystallization experiments. Within microfluidic Teflon tubing or the microfluidic circuitry of a plastic CrystalCard, ∼10–20 nl volume droplets are generated, each representing a microbatch-style crystallization experiment with a different chemical composition. The entire protein sample is utilized in crystallization experiments. Sparse-matrix screening and chemical gradient screening can be combined in one comprehensive ‘hybrid’ crystallization trial. The technology lends itself well to optimization by high-granularity gradient screening using optimization reagents such as precipitation agents, ligands or cryoprotectants.
protein crystallization; Microcapillary Protein Crystallization System
X-ray diffraction data from the targeting (FAT) domain of focal adhesion kinase (FAK) were collected from a single crystal that diffracted to 1.99 Å resolution.
X-ray diffraction data from the targeting (FAT) domain of focal adhesion kinase (FAK) were collected from a single crystal that diffracted to 1.99 Å resolution and reduced to the primitive orthorhombic lattice. A single molecule was predicted to be present in the asymmetric unit based on the Matthews coefficient. The data were phased using molecular-replacement methods using an existing model of the FAK FAT domain. All structures of human focal adhesion kinase FAT domains solved to date have been solved in a C-centered orthorhombic space group.
focal adhesion kinase; targeting domain