6M4L
X-ray crystal structure of the E249Q mutant of alpha-amylase I from Eisenia fetida
Summary for 6M4L
| Entry DOI | 10.2210/pdb6m4l/pdb |
| Descriptor | Alpha-amylase, CALCIUM ION, CHLORIDE ION, ... (10 entities in total) |
| Functional Keywords | tim barrel, gh family 13, carbohydrase, cold-active, hydrolase |
| Biological source | Eisenia fetida (Red wiggler worm) |
| Total number of polymer chains | 1 |
| Total formula weight | 59677.71 |
| Authors | Hirano, Y.,Tsukamoto, K.,Ariki, S.,Naka, Y.,Ueda, M.,Tamada, T. (deposition date: 2020-03-07, release date: 2020-09-16, Last modification date: 2024-10-16) |
| Primary citation | Hirano, Y.,Tsukamoto, K.,Ariki, S.,Naka, Y.,Ueda, M.,Tamada, T. X-ray crystallographic structural studies of alpha-amylase I from Eisenia fetida. Acta Crystallogr D Struct Biol, 76:834-844, 2020 Cited by PubMed Abstract: The earthworm Eisenia fetida possesses several cold-active enzymes, including α-amylase, β-glucanase and β-mannanase. E. fetida possesses two isoforms of α-amylase (Ef-Amy I and II) to digest raw starch. Ef-Amy I retains its catalytic activity at temperatures below 10°C. To identify the molecular properties of Ef-Amy I, X-ray crystal structures were determined of the wild type and of the inactive E249Q mutant. Ef-Amy I has structural similarities to mammalian α-amylases, including the porcine pancreatic and human pancreatic α-amylases. Structural comparisons of the overall structures as well as of the Ca-binding sites of Ef-Amy I and the mammalian α-amylases indicate that Ef-Amy I has increased structural flexibility and more solvent-exposed acidic residues. These structural features of Ef-Amy I may contribute to its observed catalytic activity at low temperatures, as many cold-adapted enzymes have similar structural properties. The structure of the substrate complex of the inactive mutant of Ef-Amy I shows that a maltohexaose molecule is bound in the active site and a maltotetraose molecule is bound in the cleft between the N- and C-terminal domains. The recognition of substrate molecules by Ef-Amy I exhibits some differences from that observed in structures of human pancreatic α-amylase. This result provides insights into the structural modulation of the recognition of substrates and inhibitors. PubMed: 32876059DOI: 10.1107/S2059798320010165 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.6 Å) |
Structure validation
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