1ECE

ACIDOTHERMUS CELLULOLYTICUS ENDOCELLULASE E1 CATALYTIC DOMAIN IN COMPLEX WITH A CELLOTETRAOSE

1ECE の概要

• エントリーDOI: 10.2210/pdb1ece/pdb
• 関連するBIRD辞書のPRD_ID: PRD_900011
• 分子名称: ENDOCELLULASE E1, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose (3 entities in total)
• 機能のキーワード: cellulase, endocellulase, glycosyl hydrolase
• 由来する生物種: Acidothermus cellulolyticus
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 81862.44

構造登録者

Sakon, J.,Thomas, S.R.,Himmel, M.E.,Karplus, P.A. (登録日: 1996-04-04, 公開日: 1996-10-14, 最終更新日: 2024-10-16)

主引用文献

Sakon, J.,Adney, W.S.,Himmel, M.E.,Thomas, S.R.,Karplus, P.A.
Crystal structure of thermostable family 5 endocellulase E1 from Acidothermus cellulolyticus in complex with cellotetraose.
Biochemistry, 35:10648-10660, 1996

PubMed Abstract: The crystal structure of the catalytic domain of the thermostable endocellulase E1 from Acidothermus cellulolyticus in complex with cellotetraose has been solved by multiple isomorphous replacement and refined at 2.4 A resolution to an R-factor of 0.18 (Rfree = 0.24). E1cd is a member of the 4/7 superfamily of hydrolases, and as expected, its structure is an (alpha/beta)8 barrel, which constitutes a prototype for family 5-subfamily 1 cellulases. The cellotetraose molecule binds in a manner consistent with the expected Michaelis complex for the glycosylation half-reaction and reveals that all eight residues conserved in family 5 enzymes are involved in recognition of the glycosyl group attacked during cleavage. Whereas only three residues are conserved in the whole 4/7 superfamily (the Asn/Glu duo and the Glu from which the name is derived), structural comparisons show that all eight residues conserved in family 5 have functional equivalents in the other 4/7 superfamily members, strengthening the case that mechanistic details are conserved throughout the superfamily. On the basis of the structure, a detailed sequence of physical steps of the cleavage mechanism is proposed. A close approach of two key glutamate residues provides an elegant mechanism for the shift in the pKa of the acid/base for the glycosylation and deglycosylation half-reactions. Finally, purely structural based comparisons are used to show that significant differences exist in structural similarity scores resulting from different methods and suggest that caution should be exercised in interpreting such results in terms of implied evolutional relationships.

PubMed: 8718854
DOI: 10.1021/bi9604439

実験手法

X-RAY DIFFRACTION (2.4 Å)