Publications by authors named "Yukuhiko Asada"

Information from structural genomics experiments at the RIKEN SPring-8 Center, Japan has been compiled and published as an integrated database. The contents of the database are (i) experimental data from nine species of bacteria that cover a large variety of protein molecules in terms of both evolution and properties (http://database.riken.

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l-Gulonate 3-dehydrogenase (GDH) is a bifunctional dimeric protein that functions not only as an NAD(+)-dependent enzyme in the uronate cycle but also as a taxon-specific lambda-crystallin in rabbit lens. Here we report the first crystal structure of GDH in both apo form and NADH-bound holo form. The GDH protomer consists of two structural domains: the N-terminal domain with a Rossmann fold and the C-terminal domain with a novel helical fold.

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Thermus thermophilus HB8 is a hyperthermophilic bacterium, thriving at environmental temperature near 80 degrees C. The genomic analysis of this bacterium predicted 18 genes for proteins belonging to the short-chain dehydrogenase/reductases (SDR) superfamily, but their functions remain unknown. A SDR encoded in a gene (TTHA0369) was chosen for functional and structural characterization.

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A high-throughput crystallization-to-structure pipeline for structural genomics was recently developed at the Advanced Protein Crystallography Research Group of the RIKEN SPring-8 Center in Japan. The structure determination pipeline includes three newly developed technologies for automating X-ray protein crystallography: the automated crystallization and observation robot system "TERA", the SPring-8 Precise Automatic Cryosample Exchanger "SPACE" for automated data collection, and the Package of Expert Researcher's Operation Network "PERON" for automated crystallographic computation from phasing to model checking. During the 5 years following April, 2002, this pipeline was used by seven researchers to determine 138 independent crystal structures (resulting from 437 purified proteins, 234 cryoloop-mountable crystals, and 175 diffraction data sets).

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Protein crystallization is still a major bottleneck in structural biology. As the current methodology of protein crystallization is a type of screening, it is usually difficult to crystallize important target proteins. It was thought that hetero-epitaxic growth from the surface of a mineral crystal acting as a nucleant would be an effective enhancer of protein crystallization.

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Mammalian dimeric dihydrodiol dehydrogenase (DD) is identical to NADP+-dependent D-xylose dehydrogenase. A recent investigation showed that the three-dimensional structure of monkey DD is similar to those of prokaryotic NADP(H)-dependent glucose-fructose oxidoreductase (GFO) and 1,5-anhydro-D-fructose reductase (AFR); however, it differs in coenzyme-binding and catalytic residues. Dimeric DD has a high affinity for NADP(H) when compared with AFR and differs from both GFO and AFR in its specificity for sugars and hydrophobic xenobiotic compounds as substrates.

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Rabbit L-gulonate 3-dehydrogenase was crystallized using the oil-microbatch method at 295 K. X-ray diffraction data were collected to 1.70 A resolution from a crystal at 100 K using synchrotron radiation.

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In order to elucidate the thermo-stabilization mechanism of the tryptophan synthase alpha-subunit from the extreme thermophile Thermus thermophilus HB8 (Tt-alpha-subunit), its crystal structure was determined and its stability was examined using DSC. The results were compared to those of other orthologs from mesophilic and hyperthermophilic organisms. The denaturation temperature of the Tt-alpha-subunit was higher than that of the alpha-subunit from S.

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Heavy-atom Database System (HATODAS) is a WWW-based tool designed to assist the heavy-atom derivatization of proteins. The conventional procedure for the preparation of derivatives is usually a time-consuming 'trial-and-error' process. The present program provides a solution for this problem using a database of known heavy-atom derivatives.

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Hot dog fold proteins sharing the characteristic "hot dog" fold are known to involve certain coenzyme A binding enzymes with various oligomeric states. In order to elucidate the oligomerization-function relationship of the hot dog fold proteins, crystal structures of the phenylacetate degradation protein PaaI from Thermus thermophilus HB8 (TtPaaI), a tetrameric acyl-CoA thioesterase with the hot dog fold, have been determined and compared with those of other family members. In the liganded crystal forms with coenzyme A derivatives, only two of four intersubunit catalytic pockets of the TtPaaI tetramer are occupied by the ligands.

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Article Synopsis
  • Dihydrodiol dehydrogenase is an enzyme that oxidizes trans-dihydrodiols of aromatic hydrocarbons to catechols and has various forms in mammalian tissues.
  • The dimeric form of this enzyme has a unique structure that suggests it may be part of a new protein family related to prokaryotic enzymes.
  • The monkey kidney version of this enzyme has been crystallized, showing high-resolution diffraction, and its crystals belong to specific hexagonal space groups with defined unit-cell parameters.
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