Crystal structure of barley 1,3-1,4-beta-glucanase at 2.0-A resolution and comparison with Bacillus 1,3-1,4-beta-glucanase

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Item Type:	Article
Title:	Crystal structure of barley 1,3-1,4-beta-glucanase at 2.0-A resolution and comparison with Bacillus 1,3-1,4-beta-glucanase
Creators Name:	Mueller, J.J., Thomsen, K.K. and Heinemann, U.
Abstract:	Both plants and bacteria produce enzymes capable of degrading the mixed-linked beta-glucan of the endosperm cell walls of cereal grains. The enzymes share the specificity for beta-1,4 glycosyl bonds of O-3-substituted glucose units in linear polysaccharides and a similar cleavage mechanism but are unrelated in sequence and tertiary structure. The three-dimensional structure of the 1,3-1, 4-beta-glucanase isoenzyme EII from barley was determined from monoclinic crystals at a resolution of 2.0 A. The protein is folded into a betaalpha8 barrel structure as has been shown previously (Varghese, J. N., Garrett, T. P. J., Colman, P. M., Chen, L., Hoj, P. B., and Fincher, G. B. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 2785-2789) by diffraction analysis at lower resolution of tetragonal crystals. It contains one N-glycosylation site which is described in detail with the sugar moieties attached to residue Asn190. The geometry and hydration of the barley 1,3-1,4-beta-glucanase is analyzed; a model beta-glucan fragment is placed into the binding site by molecular dynamics simulation, and the beta-glucan binding grooves of the plant and bacterial enzymes are compared. Their active sites are shown to have a small number of common features in generally dissimilar geometries that serve to explain both the identical substrate specificity and the observed differences in inhibitor binding.
Keywords:	Bacillus, Binding Sites, Endo-1,3(4)-beta-Glucanase, Glycoside Hydrolases, Glycosylation, Hordeum, Molecular Sequence Data, Protein Conformation, Substrate Specificity, Water, X-Ray Crystallography
Source:	Journal of Biological Chemistry
ISSN:	0021-9258
Publisher:	American Society for Biochemistry and Molecular Biology
Volume:	273
Number:	6
Page Range:	3438-3446
Date:	6 February 1998
Official Publication:	https://doi.org/10.1074/jbc.273.6.3438
PubMed:	View item in PubMed

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