論文 - 詳細
| RRC ID | 50845 |
|---|---|
| 著者 | Hayashi J, Mutaguchi Y, Minemura Y, Nakagawa N, Yoneda K, Ohmori T, Ohshima T, Sakuraba H. |
| タイトル | Crystal structure of the novel amino-acid racemase isoleucine 2-epimerase from Lactobacillus buchneri. |
| ジャーナル | Acta Crystallogr D Struct Biol |
| Abstract |
Crystal structures of Lactobacillus buchneri isoleucine 2-epimerase, a novel branched-chain amino-acid racemase, were determined for the enzyme in the apo form, in complex with pyridoxal 5'-phosphate (PLP), in complex with N-(5'-phosphopyridoxyl)-L-isoleucine (PLP-L-Ile) and in complex with N-(5'-phosphopyridoxyl)-D-allo-isoleucine (PLP-D-allo-Ile) at resolutions of 2.77, 1.94, 2.65 and 2.12 Å, respectively. The enzyme assembled as a tetramer, with each subunit being composed of N-terminal, C-terminal and large PLP-binding domains. The active-site cavity in the apo structure was much more solvent-accessible than that in the PLP-bound structure. This indicates that a marked structural change occurs around the active site upon binding of PLP that provides a solvent-inaccessible environment for the enzymatic reaction. The main-chain coordinates of the L. buchneri isoleucine 2-epimerase monomer showed a notable similarity to those of α-amino-ℇ-caprolactam racemase from Achromobactor obae and γ-aminobutyrate aminotransferase from Escherichia coli. However, the amino-acid residues involved in substrate binding in those two enzymes are only partially conserved in L. buchneri isoleucine 2-epimerase, which may account for the differences in substrate recognition by the three enzymes. The structures bound with reaction-intermediate analogues (PLP-L-Ile and PLP-D-allo-Ile) and site-directed mutagenesis suggest that L-isoleucine epimerization proceeds through abstraction of the α-hydrogen of the substrate by Lys280, while Asp222 serves as the catalytic residue adding an α-hydrogen to the quinonoid intermediate to form D-allo-isoleucine. |
| 巻・号 | 73(Pt 5) |
| ページ | 428-437 |
| 公開日 | 2017-5-1 |
| DOI | 10.1107/S2059798317005332 |
| PII | S2059798317005332 |
| PMID | 28471367 |
| MeSH | Amino Acid Isomerases / chemistry* Amino Acid Isomerases / metabolism* Amino Acid Sequence Crystallography, X-Ray Isoleucine / analogs & derivatives Isoleucine / chemistry Isoleucine / metabolism* Lactobacillus / chemistry Lactobacillus / enzymology* Lactobacillus / metabolism Models, Molecular Protein Conformation Pyridoxal Phosphate / analogs & derivatives Pyridoxal Phosphate / metabolism Sequence Alignment |
| IF | 3.099 |
| 引用数 | 6 |
| オルトメトリクス指標 |
オルトメトリクス指標項目
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| 最多言及媒体 | X(Twitter) |
| 各媒体での言及数の合計 | 2 |
| 過去6か月間でのオルトメトリクス指標の変動値 | 0.0 |
| リソース情報 | |
| 一般微生物 | JCM 1115 |