Preliminary crystallographic analysis of two hypothetical ribose-5-phosphate isomerases from Streptococcus mutans.
ABSTRACT: Study of the enzymes from sugar metabolic pathways may provide a better understanding of the pathogenesis of the human oral pathogen Streptococcus mutans. Bioinformatics, biochemical and crystallization methods were used to characterize and understand the function of two putative ribose-5-phosphate isomerases: SMU1234 and SMU2142. The proteins were cloned and constructed with N-terminal His tags. Protein purification was performed by Ni(2+)-chelating and size-exclusion chromatography. The crystals of SUM1234 diffracted to 1.9?Å resolution and belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 48.97, b = 98.27, c = 101.09?Å, ? = ? = ? = 90°. The optimized SMU2142 crystals diffracted to 2.7?Å resolution and belonged to space group P1, with unit-cell parameters a = 53.7, b = 54.1, c = 86.5?Å, ? = 74.2, ? = 73.5, ? = 83.7°. Initial phasing of both proteins was attempted by molecular replacement; the structure of SMU1234 could easily be solved, but no useful results were obtained for SMU2142. Therefore, SeMet-labelled SMU2142 will be prepared for phasing.
Project description:Bag2, an atypical member of the Bag family of Hsp70 co-chaperones, acts as both an Hsp70 nucleotide-exchange factor and an inhibitor of the Hsp70-binding E3 ubiquitin ligase CHIP (carboxyl-terminus of Hsp70-interacting protein). The amino-terminal domain of Bag2 (Bag2-NTD), which is required for inhibition of CHIP, has no sequence homologs in the PDB. Native and selenomethionyl (SeMet) forms of Bag2-NTD were crystallized by hanging-drop vapor diffusion. Native Bag2-NTD crystals diffracted to 2.27 Å resolution and belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 75.5, b = 84.7, c = 114.1 Å. SeMet Bag2-NTD crystals diffracted to 3.10 Å resolution and belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 37.2, b = 53.3, c = 86.7 Å. Phases for the SeMet Bag2-NTD crystal were solved by single-wavelength anomalous diffraction. Initial phasing and model building using the 3.10 Å resolution SeMet Bag2-NTD data set suggested that Bag2-NTD forms a dimer and adopts a fold distinct from those of any domains annotated in the Pfam or SMART domain databases.
Project description:The CsgC protein is a component of the curli system in Escherichia coli. Reported here is the successful incorporation of selenocysteine (SeCys) and selenomethionine (SeMet) into recombinant CsgC, yielding derivatized crystals suitable for structural determination. Unlike in previous reports, a standard autotrophic expression strain was used and only single-wavelength anomalous dispersion (SAD) data were required for successful phasing. The level of SeCys/SeMet incorporation was estimated by mass spectrometry to be about 80%. The native protein crystallized in two different crystal forms (form 1 belonging to space group C222(1) and form 2 belonging to space group C2), which diffracted to 2.4 and 2.0?Å resolution, respectively, whilst Se-derivatized protein crystallized in space group C2 and diffracted to 1.7?Å resolution. The Se-derivatized crystals are suitable for SAD structure determination using only the anomalous signal derived from the SeCys residues. These results extend the usability of SeCys labelling to more general and less favourable cases, rendering it a suitable alternative to traditional phasing approaches.
Project description:Terpenoids are a large and highly diverse group of natural products, with the most chemically diverse pool of structures. Terpene synthase is the key enzyme in the process of terpenoid synthesis. In this paper, the first diterpene synthase (CYC) of bacterial origin was successfully crystallized. Native and SeMet-derivative crystals diffracted to 1.75 and 2.6 Å resolution, respectively. The native crystal belonged to space group P212121, with unit-cell parameters a = 59.10, b = 101.73, c = 108.93 Å, and contained two molecules per asymmetric unit. The SeMet-derivative crystal belonged to space group P21, with unit-cell parameters a = 58.64, b = 109.47, c = 58.73 Å, β = 119.35°, and had two molecules per asymmetric unit.
Project description:The Rv0045c protein is predicted to be an esterase that is involved in lipid metabolism in Mycobacterium tuberculosis. The protein was overproduced in Escherichia coli, purified and crystallized using the hanging-drop vapour-diffusion method. The Rv0045c protein crystals diffracted to a resolution of 2.7?Å using a synchrotron-radiation source and belonged to space group P3(1) or P3(2), with unit-cell parameters a=b=73.465, c=48.064?Å, ?=?=90, ?=120°. Purified SeMet-labelled Rv0045c protein was also crystallized and formed crystals that diffracted to a resolution of 3.0?Å using an in-house X-ray radiation source.
Project description:White spot syndrome virus (WSSV) is a major shrimp pathogen known to infect penaeid shrimp and other crustaceans. VP24 is one of the major envelope proteins of WSSV. In order to facilitate purification, crystallization and structure determination, the predicted N-terminal transmembrane region of approximately 26 amino acids was truncated from VP24 and several mutants were prepared to increase the proportion of selenomethionine (SeMet) residues for subsequent structural determination using the SAD method. Truncated VP24, its mutants and the corresponding SeMet-labelled proteins were purified, and the native and SeMet proteins were crystallized by the hanging-drop vapour-diffusion method. Crystals of VP24 were obtained using a reservoir consisting of 0.1?M Tris-HCl pH 8.5, 2.75?M ammonium acetate with a drop volume ratio of two parts protein solution to one part reservoir solution. Notably, ATP was added as a critical additive to the drop with a final concentration of 10?mM. Crystals of SeMet-labelled VP24 mutant diffracted to 3.0?Å resolution and those of the native diffracted to 2.4?Å resolution; the crystals belonged to space group I213, with unit-cell parameters a = b = c = 140?Å.
Project description:The novel thermostable esterase EstL5 belonging to the GDSL family exhibits a unique cold-adaptation feature at low temperatures. To better understand its biochemical and enzymatic properties, recombinant EstL5 protein was purified and crystallized using the vapour-diffusion method. The EstL5 crystals diffracted X-rays to 2.79 Å resolution using a synchrotron-radiation source, belonged to the tetragonal space group P41212 or P43212, with unit-cell parameters a = b = 101.51, c = 124.22 Å, and are expected to contain two molecules in each asymmetric unit. To obtain initial phases, selenomethionyl-substituted protein was overproduced. Purified SeMet-labelled EstL5 protein was crystallized and formed crystals that diffracted to a resolution of 3.0 Å.
Project description:Nitroalkane oxidase (NAO) is a flavin-dependent enzyme which catalyses the oxidation of nitroalkanes to the corresponding aldehydes or ketones, nitrite and hydrogen peroxide. In order to better understand the structure and function of this enzyme, NAO from Pseudomonas aeruginosa was purified and crystallized as a native and a selenomethionine-substituted (SeMet) enzyme. Both crystals diffracted to a resolution of 1.9 Å and belonged to the primitive orthorhombic space group P2₁, with unit-cell parameters a = 70.06, b = 55.43, c = 87.74 Å, β = 96.56° for native NAO and a = 69.89, b = 54.83, c = 88.20 Å, β = 95.79° for SeMet NAO. Assuming the presence of two molecules in the asymmetric unit in both crystals, the Matthews coefficients (VM) for native and SeMet NAO were calculated to be 2.30 and 2.48 Å³ Da⁻¹, with estimated solvent contents of 46.50 and 50.37%, respectively.
Project description:In higher eukaryotes, the condensin complex, which mainly consists of two structural maintenance of chromosomes (SMC) subunits, SMC2 (CAP-E) and SMC4 (CAP-C), plays a critical role in the formation of higher order chromosome structures during mitosis. Biochemical and electron-microscopic studies have revealed that the SMC2 and SMC4 subunits dimerize through the interaction of their hinge domains, forming a characteristic V-shaped heterodimer. However, the details of their function are still not fully understood owing to a lack of structural information at the atomic level. In this study, the human SMC2 hinge domain with short coiled coils was cloned, expressed, purified and crystallized in the orthorhombic space group C222 in native and SeMet-derivatized forms. Because of the poor diffraction properties of these crystals, the mutant Leu68-->SeMet was designed and crystallized in order to obtain the experimental phases. The SeMet-derivatized crystals of the mutant belonged to space group P3(2)12, with unit-cell parameters a=b=128.8, c=91.4 A. The diffraction data obtained from a crystal that diffracted to 2.4 A resolution were suitable for SAD phasing.
Project description:V-ATPases are very complex multi-subunit enzymes which function as proton-pumping rotary nanomotors. The rotary and coupling subunit F (F(1-94)) was crystallized by the hanging-drop vapour-diffusion method. The native crystals diffracted to a resolution of 2.64 Å and belonged to space group C222(1), with unit-cell parameters a = 47.21, b = 160.26, c = 102.49 Å. The selenomethionyl form of the F(1-94) I69M mutant diffracted to a resolution of 2.3 Å and belonged to space group C222(1), with unit-cell parameters a = 47.22, b = 160.83, c = 102.74 Å. Initial phasing and model building suggested the presence of four molecules in the asymmetric unit.
Project description:A tetrahydrofolate-dependent O-demethylase, LigM, from Sphingobium sp. SYK-6 was crystallized by the hanging-drop vapour-diffusion method. However, the obtained P3121 or P3221 crystals, which diffracted to 2.5-3.3?Å resolution, were hemihedrally twinned. To overcome the twinning problem, microseeding using P3121/P3221 crystals as microseeds was performed with optimization of the reservoir conditions. As a result, another crystal form was obtained. The newly obtained crystal diffracted to 2.5-3.0?Å resolution and belonged to space group P21212, with unit-cell parameters a = 102.0, b = 117.3, c = 128.1?Å. The P21212 crystals diffracted to better than 2.0?Å resolution after optimizing the cryoconditions. Phasing using the single anomalous diffraction method was successful at 3.0?Å resolution with a Pt-derivative crystal. This experience suggested that microseeding is an effective method to overcome the twinning problem, even when twinned crystals are utilized as microseeds.