scholarly journals Successful data recovery from oscillation photographs containing strong polycrystalline diffraction rings from an unknown small-molecule contaminant: preliminary structure solution ofSalmonella typhimuriumpyridoxal kinase (PdxK)

Author(s):  
G. Deka ◽  
J. N. Kalyani ◽  
J. F. Benazir ◽  
H. S. Savithri ◽  
M. R. N. Murthy

Pyridoxal kinase (PdxK; EC 2.7.1.35) belongs to the phosphotransferase family of enzymes and catalyzes the conversion of the three active forms of vitamin B6, pyridoxine, pyridoxal and pyridoxamine, to their phosphorylated forms and thereby plays a key role in pyridoxal 5′-phosphate salvage. In the present study, pyridoxal kinase fromSalmonella typhimuriumwas cloned and overexpressed inEscherichia coli, purified using Ni–NTA affinity chromatography and crystallized. X-ray diffraction data were collected to 2.6 Å resolution at 100 K. The crystal belonged to the primitive orthorhombic space groupP212121, with unit-cell parametersa= 65.11,b= 72.89,c= 107.52 Å. The data quality obtained by routine processing was poor owing to the presence of strong diffraction rings caused by a polycrystalline material of an unknown small molecule in all oscillation images. Excluding the reflections close to powder/polycrystalline rings provided data of sufficient quality for structure determination. A preliminary structure solution has been obtained by molecular replacement with thePhaserprogram in theCCP4 suite usingE. colipyridoxal kinase (PDB entry 2ddm) as the phasing model. Further refinement and analysis of the structure are likely to provide valuable insights into catalysis by pyridoxal kinases.

Author(s):  
Silje Skråmo ◽  
Hans-Petter Hersleth ◽  
Marta Hammerstad ◽  
K. Kristoffer Andersson ◽  
Åsmund K. Røhr

Ferredoxin/flavodoxin-NADP(H) oxidoreductases (FNRs) are key enzymes involved in catalysing electron transfer between ferredoxins/flavodoxins and NAD(P)H/NAD(P)+. InBacillus cereusthere are three genes that may encode FNRs, and the Bc0385 FNR has been cloned, overexpressed, purified and successfully crystallized in its NADPH/NADP+-free form. Diffraction data have been collected to 2.5 Å resolution from crystals belonging to the orthorhombic space groupP21212, with unit-cell parametersa= 57.2,b= 164.3,c= 95.0 Å, containing two FNR molecules in the asymmetric unit. The structure of the Bc0385 FNR has been solved by molecular replacement, and is a member of the homodimeric thioredoxin reductase-like class of FNRs.


Author(s):  
Lokesh D. Kori ◽  
Andreas Hofmann ◽  
Bharat K. C. Patel

A ribokinase gene (rbk) from the anaerobic halothermophilic bacteriumHalothermothrix oreniiwas cloned and overexpressed inEscherichia coli. The recombinant protein (Ho-Rbk) was purified using immobilized metal-ion affinity chromatography and crystals were obtained using the sitting-drop method. Diffraction data were collected to a resolution of 3.1 Å using synchrotron radiation. The crystals belonged to the orthorhombic space groupP212121, with unit-cell parametersa= 45.6,b= 61.1,c= 220.2, and contained two molecules per asymmetric unit. A molecular-replacement solution has been found and attempts are currently under way to build a model of the ribokinase. Efforts to improve crystal quality so that higher resolution data can be obtained are also being considered.


Author(s):  
Muhammad Tayyab ◽  
Naeem Rashid ◽  
Clement Angkawidjaja ◽  
Shigenori Kanaya ◽  
Muhammad Akhtar

A thermoalkalophilic lipase (LIPSBS) from the newly isolatedGeobacillusstrain SBS-4S which hydrolyzes a wide range of fatty acids has been characterized. In the present study, the crystallization of purified LIPSBSusing the sitting-drop vapour-diffusion method and its X-ray diffraction studies are described. The crystals belonged to the orthorhombic space groupP212121, with unit-cell parametersa= 55.13,b= 71.75,c= 126.26 Å. The structure was determined at 1.6 Å resolution by the molecular-replacement method using the lipase fromG. stearothermophilusL1 as a model.


Author(s):  
Laura A. Lallemand ◽  
James G. McCarthy ◽  
Sean McSweeney ◽  
Andrew A. McCarthy

Chlorogenic acids (CGAs) are a group of soluble phenolic compounds that are produced by a variety of plants, includingCoffea canephora(robusta coffee). The last step in CGA biosynthesis is generally catalysed by a specific hydroxycinnamoyl-CoA quinate hydroxycinnamoyltransferase (HQT), but it can also be catalysed by the more widely distributed hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyltransferase (HCT). Here, the cloning and overexpression of HCT fromC. canephorainEscherichia colias well as its purification and crystallization are presented. Crystals were obtained by the sitting-drop technique at 293 K and X-ray diffraction data were collected on the microfocus beamline ID23-2 at the ESRF. The HCT crystals diffracted to better than 3.0 Å resolution, belonged to space groupP42212 with unit-cell parametersa=b= 116.1,c= 158.9 Å and contained two molecules in the asymmetric unit. The structure was solved by molecular replacement and is currently under refinement. Such structural data are needed to decipher the molecular basis of the substrate specifities of this key enzyme, which belongs to the large plant acyl-CoA-dependent BAHD acyltransferase superfamily.


Author(s):  
Ruyi Ding ◽  
Cui Xu ◽  
Xu Chen ◽  
Mengyun Bao ◽  
Xiaoting Qiu

The 2-carboxy-6-hydroxyoctahydroindole moiety is an essential residue for the antithrombotic activity of aeruginosins, which are a class of cyanobacteria-derived bioactive linear tetrapeptides. The biosynthetic pathway of the 2-carboxy-6-hydroxyoctahydroindole moiety has not yet been resolved. AerF was indicated to be involved in the biosynthesis of the 2-carboxy-6-hydroxyoctahydroindole moiety. This study reports the cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of AerF fromMicrocystis aeruginosawith a C-terminal His6tag. The crystal diffracted to a maximum resolution of 1.38 Å and belonged to the tetragonal space groupP4322, with unit-cell parametersa=b= 101.581,c= 116.094 Å. The calculated Matthews coefficient and solvent content of the crystal were 2.47 Å3 Da−1and 50.32%, respectively. The initial model of the structure was obtained by the molecular-replacement method and refinement of the structure is in progress.


Author(s):  
Abyson Joseph ◽  
Valakunja Nagaraja ◽  
Ramanathan Natesh

The transcriptional activity of RNA polymerase (RNAP) is controlled by a diverse set of regulatory factors. A subset of these regulators modulate the activity of RNAP through its secondary channel. Gre factors reactivate stalled elongation complexes by enhancing the intrinsic cleavage activity of RNAP. In the present study, the protein MSMEG_6292, a Gre-factor homologue from Mycobacterium smegmatis, was expressed heterologously in Escherichia coli and purified using standard chromatographic techniques. The hanging-drop vapour-diffusion crystallization method yielded diffraction-quality crystals. The crystals belonged to the trigonal space group P3121 (or its enantiomorph P3221), with unit-cell parameters a = b = 83.15, c = 107.07 Å, α = β = 90, γ = 120°. The crystals diffracted to better than 3.0 Å resolution. Molecular-replacement attempts did not yield any phasing models; hence, platinum derivatization was carried out with K2PtCl4 and derivative data were collected to 3.4 Å resolution.


2014 ◽  
Vol 70 (12) ◽  
pp. 1640-1642 ◽  
Author(s):  
Yongbin Xu ◽  
Chun-Shan Quan ◽  
Xuanzhen Jin ◽  
Xiaoling Jin ◽  
Jing Zhao ◽  
...  

Universal stress proteins (Usps) are among the most highly induced genes when bacteria are subjected to several stress conditions such as heat shock, nutrient starvation or the presence of oxidants or other stress agents.Escherichia colihas five small Usps and one tandem-type Usp. UspE (or YdaA) is the tandem-type Usp and consists of two Usp domains arranged in tandem. To date, the structure of UspE remains to be elucidated. To contribute to the molecular understanding of the function of the tandem-type UspE, UspE fromE. coliwas overexpressed and the recombinant protein was purified using Ni–NTA affinity, Q anion-exchange and gel-filtration chromatography. Crystals of UspE were obtained by sitting-drop vapour diffusion. A diffraction data set was collected to a resolution of 3.2 Å from flash-cooled crystals. The crystals belonged to the tetragonal space groupI4122 orI4322, with unit-cell parametersa=b= 121.1,c = 241.7 Å.


Author(s):  
Michael R. Jackson ◽  
Thomas L. Selby

A recombinant metal-dependent phosphatidylinositol-specific phospholipase C (PI-PLC) fromStreptomyces antibioticushas been crystallized by the hanging-drop method with and without heavy metals. The native crystals belonged to the orthorhombic space groupP222, with unit-cell parametersa= 41.26,b= 51.86,c = 154.78 Å. The X-ray diffraction results showed significant differences in the crystal quality of samples soaked with heavy atoms. Additionally, drop pinning, which increases the surface area of the drops, was also used to improve crystal growth and quality. The combination of heavy-metal soaks and drop pinning was found to be critical for producing high-quality crystals that diffracted to 1.23 Å resolution.


Author(s):  
Inês B. Trindade ◽  
Bruno M. Fonseca ◽  
Pedro M. Matias ◽  
Ricardo O. Louro ◽  
Elin Moe

Siderophore-binding proteins (SIPs) perform a key role in iron acquisition in multiple organisms. In the genome of the marine bacteriumShewanella frigidimarinaNCIMB 400, the gene tagged as SFRI_RS12295 encodes a protein from this family. Here, the cloning, expression, purification and crystallization of this protein are reported, together with its preliminary X-ray crystallographic analysis to 1.35 Å resolution. The SIP crystals belonged to the monoclinic space groupP21, with unit-cell parametersa= 48.04,b= 78.31,c= 67.71 Å, α = 90, β = 99.94, γ = 90°, and are predicted to contain two molecules per asymmetric unit. Structure determination by molecular replacement and the use of previously determined ∼2 Å resolution SIP structures with ∼30% sequence identity as templates are ongoing.


Author(s):  
Cristian Biagioni ◽  
Luca Bindi ◽  
Koichi Momma ◽  
Ritsuro Miyawaki ◽  
Yoshitaka Matsushita ◽  
...  

Abstract Tsugaruite was originally defined as a lead-arsenic sulfosalt from the Yunosawa mine, Aomori Prefecture, Japan. Until recently its crystal structure remained unsolved and its actual classification in the sulfosalt realm was unknown. Here the refinement of the crystal structure of tsugaruite using single-crystal X-ray diffraction data is reported. The mineral is orthorhombic, space group P2nn, with unit-cell parameters a = 8.0774(10), b = 15.1772(16), c = 38.129(4) Å, V = 4674.3(9) Å3, in agreement with previous studies. The solution of the crystal structure of this mineral revealed Cl occupying a specific position. Chlorine was thus sought and found using the electron microprobe; the average of six spot analyses gave (in wt.%): Pb 68.04, As 12.83, S 18.29, Cl 0.63, total 99.80. The empirical formula, calculated on the basis of Pb + As = 43 atoms per formula unit, is Pb28.26As14.74S49.08Cl1.52. Tsugaruite is an N = 4 plesiotypic derivative of the homologous series of Pb-Sb chloro-sulfosalts having the general formula Pb(2+2N)(Sb,Pb)(2+2N)S(2+2N)(S,Cl)(4+2N)ClN. It has a Cl/(Cl + S) atomic ratio close to that of other known Pb-Sb chloro-sulfosalts (pillaite, pellouxite) and slightly higher than that of dadsonite.


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