scholarly journals An extracellular domain of the EsaA membrane component of the type VIIb secretion system: expression, purification and crystallization

Author(s):  
Nicole Mietrach ◽  
Andreas Schlosser ◽  
Sebastian Geibel

The membrane protein EsaA is a conserved component of the type VIIb secretion system. Limited proteolysis of purified EsaA from Staphylococcus aureus USA300 identified a stable 48 kDa fragment, which was mapped by fingerprint mass spectrometry to an uncharacterized extracellular segment of EsaA. Analysis by circular dichroism spectroscopy showed that this fragment folds into a single stable domain made of mostly α-helices with a melting point of 34.5°C. Size-exclusion chromatography combined with multi-angle light scattering indicated the formation of a dimer of the purified extracellular domain. Octahedral crystals were grown in 0.2 M ammonium citrate tribasic pH 7.0, 16% PEG 3350 using the hanging-drop vapor-diffusion method. Diffraction data were analyzed to 4.0 Å resolution, showing that the crystals belonged to the enantiomorphic tetragonal space groups P41212 or P43212, with unit-cell parameters a = 197.5, b = 197.5, c = 368.3 Å, α = β = γ = 90°.

2014 ◽  
Vol 70 (10) ◽  
pp. 1431-1433 ◽  
Author(s):  
Gitte Meriläinen ◽  
Rik K. Wierenga

The inner membrane ring of the bacterial type III secretion system (TTSS) is composed of two proteins. InChlamydia trachomatisthis ring is formed by CdsD (gene nameCT_664) and CdsJ (gene nameCTA_0609). CdsD consists of 829 amino acids. The last 400 amino acids at its C-terminal end relate it to the type III secretion system YscD/HrpQ protein family. The C-terminal domain, consisting of amino acids 558–771, ofC. trachomatisCdsD was overexpressed inEscherichia coliand purified using immobilized metal-affinity chromatography (IMAC) and size-exclusion chromatography. The protein was crystallized using the vapour-diffusion method. A data set was collected to 2.26 Å resolution. The crystals have the symmetry of space groupC2, with unit-cell parametersa= 106.60,b= 23.91,c= 118.65 Å, β = 104.95°. According to the data analysis there is expected to be one molecule in the asymmetric unit, with a Matthews coefficient of 3.0 Å3 Da−1.


Author(s):  
Abha Jain ◽  
Dinakar Masanu Salunke

Solanum melongena(eggplant), a member of the Solanaceae family, is a widely cultivated vegetable crop and is commonly used as a food throughout the world. Allergic reactions caused by members of this family are well known. However, mechanistic analyses to understand their molecular basis have not been adequately explored. In order to address this issue, the 7S vicilin protein (SM80.1) of size 45 kDa was purified from seeds ofS. melongenaby ammonium sulfate fractionation and size-exclusion chromatography. Significant homology of SM80.1 to an allergy-related protein fromS. lycopersicumwas identified through aBLASTsearch. Crystallization attempts with purified protein using the hanging-drop vapour-diffusion method led to hexagonal-shaped crystals. The crystals diffracted to 2.21 Å resolution and belonged to space groupP6322, with unit-cell parametersa= 117.9,c= 123.5 Å.


Author(s):  
Hyun Kim ◽  
Ae Kyung Park ◽  
Jun Hyuck Lee ◽  
Seung Chul Shin ◽  
Hyun Park ◽  
...  

Esterases are very useful biocatalysts in industry: they hydrolyze esters and split them into a carboxylic acid and an alcohol. The psychrophilic esterase PsEst3 was obtained from Paenibacillus sp. R4, which was isolated from the active layer of the permafrost in Council, Alaska. PsEst3 was successfully overexpressed using a psychrophilic chaperonin co-expression system and was purified by nickel-affinity and size-exclusion chromatography. Recombinant PsEst3 was crystallized at 290 K using the hanging-drop vapour-diffusion method. X-ray diffraction data were collected to 2.1 Å resolution. The crystal was determined to belong to space group P4132 or P4332, with unit-cell parameters a = b = c = 145.33 Å. Further crystallographic analysis needs to be conducted to investigate the structure and function of this esterase.


Author(s):  
Asaithambi Killivalavan ◽  
Ningning Zhuang ◽  
Young Shik Park ◽  
Kon Ho Lee

A UDP-glucose:tetrahydrobiopterin α-glucosyltransferase (BGluT) enzyme was discovered in the cyanobacteriumSynechococcussp. PCC 7942 which transfers a glucose moiety from UDP-glucose to tetrahydrobiopterin (BH4). BGluT protein was overexpressed with selenomethionine labelling for structure determination by the multi-wavelength anomalous dispersion method. The BGluT protein was purified by nickel-affinity and size-exclusion chromatography. It was then crystallized by the hanging-drop vapour-diffusion method using a well solution consisting of 0.1 Mbis-tris pH 5.5, 19%(w/v) polyethylene glycol 3350 with 4%(w/v) D(+)-galactose as an additive. X-ray diffraction data were collected to 1.99 Å resolution using a synchrotron-radiation source. The crystals belonged to the monoclinic space groupC2, with unit-cell parametersa= 171.35,b= 77.99,c = 53.77 Å, β = 90.27°.


Author(s):  
Xiao Zhang ◽  
Xi-Mei Xue ◽  
Yu Yan ◽  
Jun Ye

ArsH is an NADPH-dependent flavin mononucleotide reductase and is frequently encoded as part of anarsoperon. The function of thearsHgene remains to be characterized. Crystallization and structural studies may contribute to elucidating the specific biological function of ArsH associated with arsenic resistance. ArsH fromSynechocystissp. strain PCC 6803 was overproduced, purified and crystallized. Crystals were obtained by the sitting-drop vapour-diffusion method. Diffraction data were collected and processed to a resolution of 1.6 Å. The crystals belonged to the tetragonal space groupI4122, with unit-cell parametersa=b= 127.94,c= 65.86 Å and one molecule in the asymmetric unit. Size-exclusion chromatography and molecular-replacement results showed that the ArsH formed a tetramer. Further structural analysis and comparison with ArsH fromSinorhizobium melilotiwill provide information about the oligomerization of ArsH.


2014 ◽  
Vol 70 (10) ◽  
pp. 1362-1367 ◽  
Author(s):  
Emmanuel Nji ◽  
Dianfan Li ◽  
Declan A. Doyle ◽  
Martin Caffrey

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 fromPseudomonas aeruginosawas recombinantly expressed inEscherichia coliand 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 groupP21, with unit-cell parametersa= 169.53,b= 169.53,c= 290.13 Å, γ = 120°.


Author(s):  
Santhosh Gatreddi ◽  
Sayanna Are ◽  
Insaf Ahmed Qureshi

Leishmaniais an auxotrophic protozoan parasite which acquires D-ribose by transporting it from the host cell and also by the hydrolysis of nucleosides. The enzyme ribokinase (RK) catalyzes the first step of ribose metabolism by phosphorylating D-ribose using ATP to produce D-ribose-5-phosphate. To understand its structure and function, the gene encoding RK fromL. donovaniwas cloned, expressed and purified using affinity and size-exclusion chromatography. Circular-dichroism spectroscopy of the purified protein showed comparatively more α-helix in the secondary-structure content, and thermal unfolding revealed theTmto be 317.2 K. Kinetic parameters were obtained by functional characterization ofL. donovaniRK, and theKmvalues for ribose and ATP were found to be 296 ± 36 and 116 ± 9.0 µM, respectively. Crystals obtained by the hanging-drop vapour-diffusion method diffracted to 1.95 Å resolution and belonged to the hexagonal space groupP61, with unit-cell parametersa=b= 100.25,c= 126.77 Å. Analysis of the crystal content indicated the presence of two protomers in the asymmetric unit, with a Matthews coefficient (VM) of 2.45 Å3 Da−1and 49.8% solvent content. Further study revealed that human counterpart of this protein could be used as a template to determine the first three-dimensional structure of the RK from trypanosomatid parasites.


2018 ◽  
Vol 115 (23) ◽  
pp. 5950-5955 ◽  
Author(s):  
Bastien Casu ◽  
Charline Mary ◽  
Aleksandr Sverzhinsky ◽  
Aurélien Fouillen ◽  
Antonio Nanci ◽  
...  

Type IV secretion systems (T4SSs) are multiprotein assemblies that translocate macromolecules across the cell envelope of bacteria. X-ray crystallographic and electron microscopy (EM) analyses have increasingly provided structural information on individual T4SS components and on the entire complex. As of now, relatively little information has been available on the exact localization of the inner membrane-bound T4SS components, notably the mostly periplasmic VirB8 protein and the very hydrophobic VirB6 protein. We show here that the membrane-bound, full-length version of the VirB8 homolog TraE from the plasmid pKM101 secretion system forms a high-molecular-mass complex that is distinct from the previously characterized periplasmic portion of the protein that forms dimers. Full-length TraE was extracted from the membranes with detergents, and analysis by size-exclusion chromatography, cross-linking, and size exclusion chromatography (SEC) multiangle light scattering (MALS) shows that it forms a high-molecular-mass complex. EM and small-angle X-ray scattering (SAXS) analysis demonstrate that full-length TraE forms a hexameric complex with a central pore. We also overproduced and purified the VirB6 homolog TraD and show by cross-linking, SEC, and EM that it binds to TraE. Our results suggest that TraE and TraD interact at the substrate translocation pore of the secretion system.


Author(s):  
Dan Huang ◽  
Yanan Zhang ◽  
Yanxiang Zhao ◽  
Junfeng Liu ◽  
You-Liang Peng

RGA5-A, a component of the Pia resistance-protein complex (RGA4/RGA5-A) fromOryza sativaL.japonica, has the ability to interact physically with the effector protein AVR-Pia fromMagnaporthe oryzaeviaits effector-interaction domain RGA5-A_S. The interaction between RGA5-A and AVR-Pia relieves the repression of RGA4, leading to AVR-independent cell death by the freed RGA4. To further understand the details of this interaction, the effector-interaction domain RGA5-A_S was expressed inEscherichia coliand purified to homogeneity. The purified recombinant protein His-RGA5-A_S was successfully crystallized using the sitting-drop vapour-diffusion method. A single crystal obtained using 0.2Mammonium citrate, 25%(w/v) PEG 3350 diffracted to 2.43 Å resolution. It belonged to space groupP4122 orP4322, with unit-cell parametersa=b= 55.2,c= 78.2 Å, α = β = γ = 90°.


2015 ◽  
Vol 71 (11) ◽  
pp. 1396-1400 ◽  
Author(s):  
Sze Lei Pang ◽  
Kok Lian Ho ◽  
Jitka Waterman ◽  
Aik-Hong Teh ◽  
Fook Tim Chew ◽  
...  

Dermatophagoides farinaeis one of the major house dust mite (HDM) species that cause allergic diseases. N-terminally His-tagged recombinant Der f 21 (rDer f 21), a group 21 allergen, with the signal peptide truncated was successfully overexpressed in anEscherichia coliexpression system. The purified rDer f 21 protein was initially crystallized using the sitting-drop vapour-diffusion method. Well diffracting protein crystals were obtained after optimization of the crystallization conditions using the hanging-drop vapour-diffusion method with a reservoir solution consisting of 0.19 MTris–HCl pH 8.0, 32% PEG 400 at 293 K. X-ray diffraction data were collected to 1.49 Å resolution using an in-house X-ray source. The crystal belonged to theC-centered monoclinic space groupC2, with unit-cell parametersa= 123.46,b= 27.71,c= 90.25 Å, β = 125.84°. The calculated Matthews coefficient (VM) of 2.06 Å3 Da−1suggests that there are two molecules per asymmetric unit, with a solvent content of 40.3%. Despite sharing high sequence identity with Blo t 5 (45%) and Blo t 21 (41%), both of which were determined to be monomeric in solution, size-exclusion chromatography, static light scattering and self-rotation function analysis indicate that rDer f 21 is likely to be a dimeric protein.


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