1e1e
From Proteopedia
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==Overview== | ==Overview== | ||
| - | The maize beta-glucosidase isoenzymes ZMGlu1 and ZMGlu2 hydrolyse the | + | The maize beta-glucosidase isoenzymes ZMGlu1 and ZMGlu2 hydrolyse the abundant natural substrate DIMBOAGlc (2-O-beta-D-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one), whose aglycone DIMBOA (2,4-hydroxy-7-methoxy-1,4-benzoxazin-3-one) is the major defence chemical protecting seedlings and young plant parts against herbivores and other pests. The two isoenzymes hydrolyse DIMBOAGlc with similar kinetics but differ from each other and their sorghum homologues with respect to specificity towards other substrates. To gain insights into the mechanism of substrate (i.e. aglycone) specificity between the two maize isoenzymes and their sorghum homologues, ZMGlu1 was produced in Escherichia coli, purified, crystallized and its structure solved at 2.5 Angstrom resolution by X-ray crystallography. In addition, the complex of ZMGlu1 with the non-hydrolysable inhibitor p-nitrophenyl beta-D-thioglucoside was crystallized and, based on the partial electron density, a model for the inhibitor molecule within the active site is proposed. The inhibitor is located in a slot-like active site where its aromatic aglycone is held by stacking interactions with Trp-378. Whereas some of the atoms on the non-reducing end of the glucose moiety can be modelled on the basis of the electron density, most of the inhibitor atoms are highly disordered. This is attributed to the requirement of the enzyme to accommodate two different species, namely the substrate in its ground state and in its distorted conformation, for catalysis. |
==About this Structure== | ==About this Structure== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Zea mays]] | [[Category: Zea mays]] | ||
| - | [[Category: Bevan, D | + | [[Category: Bevan, D R.]] |
[[Category: Cicek, M.]] | [[Category: Cicek, M.]] | ||
[[Category: Czjzek, M.]] | [[Category: Czjzek, M.]] | ||
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[[Category: retention of the anomeric configuration]] | [[Category: retention of the anomeric configuration]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:22:47 2008'' |
Revision as of 10:22, 21 February 2008
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CRYSTAL STRUCTURE OF A MONOCOT (MAIZE ZMGLU1) BETA-GLUCOSIDASE
Overview
The maize beta-glucosidase isoenzymes ZMGlu1 and ZMGlu2 hydrolyse the abundant natural substrate DIMBOAGlc (2-O-beta-D-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one), whose aglycone DIMBOA (2,4-hydroxy-7-methoxy-1,4-benzoxazin-3-one) is the major defence chemical protecting seedlings and young plant parts against herbivores and other pests. The two isoenzymes hydrolyse DIMBOAGlc with similar kinetics but differ from each other and their sorghum homologues with respect to specificity towards other substrates. To gain insights into the mechanism of substrate (i.e. aglycone) specificity between the two maize isoenzymes and their sorghum homologues, ZMGlu1 was produced in Escherichia coli, purified, crystallized and its structure solved at 2.5 Angstrom resolution by X-ray crystallography. In addition, the complex of ZMGlu1 with the non-hydrolysable inhibitor p-nitrophenyl beta-D-thioglucoside was crystallized and, based on the partial electron density, a model for the inhibitor molecule within the active site is proposed. The inhibitor is located in a slot-like active site where its aromatic aglycone is held by stacking interactions with Trp-378. Whereas some of the atoms on the non-reducing end of the glucose moiety can be modelled on the basis of the electron density, most of the inhibitor atoms are highly disordered. This is attributed to the requirement of the enzyme to accommodate two different species, namely the substrate in its ground state and in its distorted conformation, for catalysis.
About this Structure
1E1E is a Single protein structure of sequence from Zea mays. Active as Beta-glucosidase, with EC number 3.2.1.21 Known structural/functional Sites: and . Full crystallographic information is available from OCA.
Reference
Crystal structure of a monocotyledon (maize ZMGlu1) beta-glucosidase and a model of its complex with p-nitrophenyl beta-D-thioglucoside., Czjzek M, Cicek M, Zamboni V, Burmeister WP, Bevan DR, Henrissat B, Esen A, Biochem J. 2001 Feb 15;354(Pt 1):37-46. PMID:11171077
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