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1.  Crystallization and preliminary X-ray diffraction analysis of an archaeal tRNA-modification enzyme, TiaS, complexed with tRNAIle2 and ATP 
A. fulgidus TiaS was cocrystallized with tRNAIle2 and ATP and X-ray diffraction data were collected to 2.9 Å resolution using a synchrotron-radiation source.
The cytidine at the first anticodon position of archaeal tRNAIle2, which decodes the isoleucine AUA codon, is modified to 2-agmatinylcytidine (agm2C) to guarantee the fidelity of protein biosynthesis. This post-transcriptional modification is catalyzed by tRNAIle-agm2C synthetase (TiaS) using ATP and agmatine as substrates. Archaeoglobus fulgidus TiaS was overexpressed in Escherichia coli cells and purified. tRNAIle2 was prepared by in vitro transcription with T7 RNA polymerase. TiaS was cocrystallized with both tRNAIle2 and ATP by the vapour-diffusion method. The crystals of the TiaS–tRNAIle2–ATP complex diffracted to 2.9 Å resolution using synchrotron radiation at the Photon Factory. The crystals belonged to the primitive hexagonal space group P3221, with unit-cell parameters a = b = 131.1, c = 86.6 Å. The asymmetric unit is expected to contain one TiaS–tRNAIle2–ATP complex, with a Matthews coefficient of 2.8 Å3 Da−1 and a solvent content of 61%.
doi:10.1107/S1744309111034890
PMCID: PMC3212464  PMID: 22102245
TiaS; Archaeoglobus fulgidus; tRNAIle2; agmatine; post-transcriptional modification; anticodon
2.  Crystallization and preliminary X-ray diffraction analysis of a class V chitinase from Nicotiana tabacum  
N. tabacum class V chitinase has been crystallized. X-ray diffraction data were collected to 1.2 Å resolution using a synchrotron-radiation source.
The plant chitinases, which have been implicated in self-defence against pathogens, are divided into at least five classes (classes I, II, III, IV and V). Although the crystal structures of several plant chitinases have been solved, no crystal structure of a class V chitinase has been reported to date. Here, the crystallization of Nicotiana tabacum class V chitinase (NtChiV) using the vapour-diffusion method is reported. The NtChiV crystals diffracted to 1.2 Å resolution using synchrotron radiation at the Photon Factory. The crystals belonged to the orthorhombic space group P21212, with unit-cell parameters a = 62.4, b = 120.3, c = 51.9 Å. The asymmetric unit of the crystals is expected to contain one molecule.
doi:10.1107/S1744309110039060
PMCID: PMC2998363  PMID: 21139204
Nicotiana tabacum; defence proteins; class V chitinases
3.  Crystallization and preliminary X-ray diffraction analysis of the tRNA-modification enzyme GidA from Aquifex aeolicus  
A. aeolicus GidA has been crystallized in two different crystal forms: forms I and II. X-ray diffraction data were collected to 3.2 and 2.3 Å resolution, respectively, using a synchrotron-radiation source.
The 5-carboxymethylaminomethyl modification of uridine at the first position of the tRNA anticodon is crucial for accurate protein synthesis by stabilizing the correct codon–anticodon pairing on the ribosome. Two conserved enzymes, GidA and MnmE, are involved in this modification process. Aquifex aeolicus GidA was crystallized in two different crystal forms: forms I and II. These crystals diffracted to 3.2 and 2.3 Å resolution, respectively, using synchrotron radiation at the Photon Factory. These crystals belonged to space groups I212121 and P21 with unit-cell parameters a = 101.6, b = 213.3, c = 231.7 Å and a = 119.4, b = 98.0, c = 129.6 Å, β = 90.002°, respectively. The asymmetric units of these crystals are expected to contain two and four molecules, respectively.
doi:10.1107/S1744309109013591
PMCID: PMC2675597  PMID: 19407389
GidA; Aquifex aeolicus; tRNA; anticodon; modification
4.  Crystallization and preliminary X-ray analysis of the tRNA thiolation enzyme MnmA from Escherichia coli complexed with tRNAGlu  
The RNA thiouridylase MnmA in complex with tRNA was crystallized with and without ATP in three different crystal forms, which may reflect distinct sulfuration-reaction stages.
MnmA catalyzes a sulfuration reaction to synthesize 2-thiouridine at the wobble positions of tRNAGlu, tRNAGln and tRNALys in Escherichia coli. The binary complex of MnmA and tRNAGlu was crystallized in two different crystal forms: forms I and II. Cocrystallization of MnmA–tRNAGlu with ATP yielded form III crystals. The three crystal forms diffracted to 3.1, 3.4 and 3.4 Å resolution, respectively, using synchrotron radiation at SPring-8. These crystals belong to space groups C2, I212121 and C2, with unit-cell parameters a = 225.4, b = 175.8, c = 53.0 Å, β = 101.6°, a = 101.5, b = 108.0, c = 211.2 Å and a = 238.1, b = 102.1, c = 108.2 Å, β = 117.0°, respectively. The asymmetric units of these crystals are expected to contain two, one and two MnmA–tRNAGlu complexes, respectively.
doi:10.1107/S174430910600738X
PMCID: PMC2222564  PMID: 16582487
MnmA; tRNA; ATP; Escherichia coli
5.  Purification, crystallization and preliminary X-ray diffraction of SecDF, a translocon-associated membrane protein, from Thermus thermophilus  
SecDF is a multi-path membrane protein required for efficient protein translocation and integration via translocon. Purification and crystallization of T. thermophilus SecDF have been achieved by exploiting unique crystallization techniques that allowed the collection of a 3.74 Å data set.
Thermus thermophilus has a multi-path membrane protein, TSecDF, as a single-chain homologue of Escherichia coli SecD and SecF, which form a translocon-associated complex required for efficient preprotein translocation and membrane-protein integration. Here, the cloning, expression in E. coli, purification and crystallization of TSecDF are reported. Overproduced TSecDF was solubilized with dodecylmaltoside, chromatographically purified and crystallized by vapour diffusion in the presence of polyethylene glycol. The crystals yielded a maximum resolution of 4.2 Å upon X-ray irradiation, revealing that they belonged to space group P43212. Attempts were made to improve the diffraction quality of the crystals by combinations of micro-stirring, laser-light irradiation and dehydration, which led to the eventual collection of complete data sets at 3.74 Å resolution and preliminary success in the single-wavelength anomalous dispersion analysis. These results provide information that is essential for the determination of the three-dimensional structure of this important membrane component of the protein-translocation machinery.
doi:10.1107/S1744309106007779
PMCID: PMC2222563  PMID: 16582489
SecDF; membrane proteins; protein translocation; dehydration

Results 1-5 (5)