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-Structure paper
| タイトル | The variable structural flexibility of the Bacillus circulans β-galactosidase isoforms determines their unique functionalities. |
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| ジャーナル・号・ページ | Structure, Vol. 32, Issue 11, Page 2023-22037.e5, Year 2024 |
| 掲載日 | 2024年9月26日 |
著者 | Michaela Hovorková / Barbora Kaščáková / Lucie Petrásková / Petra Havlíčková / Jiří Nováček / Daniel Pinkas / Zdenko Gardian / Vladimír Křen / Pavla Bojarová / Ivana Kutá Smatanová / ![]() |
| PubMed 要旨 | β-Galactosidase from Bacillus circulans ATCC 31382 (BgaD) is a biotechnologically important enzyme for the synthesis of β-galactooligosaccharides (GOS). Among its four isoforms, isoform A (BgaD-A) ...β-Galactosidase from Bacillus circulans ATCC 31382 (BgaD) is a biotechnologically important enzyme for the synthesis of β-galactooligosaccharides (GOS). Among its four isoforms, isoform A (BgaD-A) has distinct synthetic properties. Here, we present cryoelectron microscopy (cryo-EM) structures of BgaD-A and compare them with the known X-ray crystal structure of isoform D (BgaD-D), revealing substantial structural divergences between the two isoforms. In contrast to BgaD-D, BgaD-A features a flexible Big-4 domain and another enigmatic domain. The newly identified flexible region in BgaD-A is termed as "barrier domain 8," and serves as a barricade, obstructing the access of longer oligosaccharide substrates into the active site of BgaD-A. The transgalactosylation reactions catalyzed by both isoforms revealed that BgaD-A has a higher selectivity than BgaD-D in the earlier stages of the reaction and is prevailingly directed to shorter galactooligosaccharides. This study improves our understanding of the structural determinants governing β-galactosidase catalysis, with implications for tailored GOS production. |
リンク | Structure / PubMed:39353423 |
| 手法 | EM (単粒子) |
| 解像度 | 3.2 - 4.0 Å |
| 構造データ | EMDB-18108, PDB-8q2h: EMDB-18153, PDB-8q4y: EMDB-18157, PDB-8q51: |
| 由来 |
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キーワード | HYDROLASE / Galactosidase / Transgalactosylation / Izoform A / Enzyme |
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niallia circulans subsp. circulans (バクテリア)
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