title: Crystal structure of endo-1,4-β-glucanase from Eisenia fetida.
abstract: The saccharification process is essential for bioethanol production from woody biomass including celluloses. Cold-adapted cellulase, which has sufficient activity at low temperature (<293 K), is capable of reducing heating costs during the saccharification process and is suitable for simultaneous saccharification and fermentation. Endo-1,4-β-glucanase from the earthworm Eisenia fetida (EF-EG2) belonging to glycoside hydrolase family 9 has been shown to have the highest activity at 313 K, and also retained a comparatively high activity at 283 K. The recombinant EF-EG2 was purified expressed in Pichia pastoris, and then grew needle-shaped crystals with dimensions of 0.02 × 0.02 × 1 mm. The crystals belonged to the space group P3221 with unit-cell parameters of a = b = 136 Å, c = 55.0 Å. The final model of EF-EG2, including 435 residues, two ions, seven crystallization reagents and 696 waters, was refined to a crystallographic R-factor of 14.7% (free R-factor of 16.8%) to 1.5 Å resolution. The overall structure of EF-EG2 has an (α/α)6 barrel fold which contains a putative active-site cleft and a negatively charged surface. This structural information helps us understand the catalytic and cold adaptation mechanisms of EF-EG2.
authors.affiliation: Quantum Beam Science Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Ibaraki 319-1195, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Arimori
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ito
authors.forename: Masami
authors.initials: M
authors.lastname: Nakazawa
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Ueda
authors.forename: Taro
authors.initials: T
authors.lastname: Tamada
mesh_terms: D000818:Animals; D001483:Base Sequence; D020134:Catalytic Domain; D002480:Cellulase / Q000737:chemistry*; D018360:Crystallography, X-Ray; D017931:DNA Primers; D009835:Oligochaeta / Q000201:enzymology*; D016133:Polymerase Chain Reaction; D011487:Protein Conformation
chemical_list: D017931:DNA Primers; D002480:Cellulase
keywords: Eisenia fetida; cold-adapted enzyme; endoglucanase; glycoside hydrolase family 9