PDBsum entry 1e1f

Hydrolase

PDB id: 1e1f

Contents

Protein chains

490 a.a. *

Ligands

PSG ×2

Waters ×356

* Residue conservation analysis

PDB id:

1e1f

Name:

Hydrolase

Title:

Crystal structure of a monocot (maize zmglu1) beta-glucosidase in complex with p-nitrophenyl-beta-d-thioglucoside

Structure:

Beta-glucosidase. Chain: a, b. Engineered: yes

Source:

Zea mays. Maize. Organism_taxid: 4577. Strain: cv. Mutin. Tissue: coleoptile. Organelle: chloroplast. Expressed in: escherichia coli. Expression_system_taxid: 562. Expression_system_cell: plys s cells.

Resolution:

2.60Å R-factor: 0.199 R-free: 0.252

Authors:

M.Czjzek,M.Cicek,D.R.Bevan,B.Henrissat,A.Esen

Key ref:

M.Czjzek et al. (2001). Crystal structure of a monocotyledon (maize ZMGlu1) beta-glucosidase and a model of its complex with p-nitrophenyl beta-D-thioglucoside. Biochem J, 354, 37-46. PubMed id: 11171077

Date:

03-May-00 Release date: 19-Feb-01

Protein chains

P49235  (HGGL1_MAIZE) -  4-hydroxy-7-methoxy-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl glucoside beta-D-glucosidase 1, chloroplastic from Zea mays

Seq: 566 a.a.

Struc: 490 a.a.

Enzyme reactions

• Enzyme class 2: E.C.3.2.1.182 - 4-hydroxy-7-methoxy-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl glucoside
• Reaction:
  1. DIMBOA beta-D-glucoside + H2O = DIMBOA + D-glucose
  2. DIBOA beta-D-glucoside + H2O = DIBOA + D-glucose

DIMBOA beta-D-glucoside + H2O = DIMBOA + D-glucose (Bound ligand (Het Group name = PSG) matches with 50.00% similarity)

DIBOA beta-D-glucoside + H2O = DIBOA + D-glucose (Bound ligand (Het Group name = PSG) matches with 50.00% similarity)

• Enzyme class 3: E.C.3.2.1.21 - beta-glucosidase.
• Reaction: Hydrolysis of terminal, non-reducing beta-D-glucose residues with release of beta-D-glucose.

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

Biochem J 354:37-46 (2001)

PubMed id: 11171077

Crystal structure of a monocotyledon (maize ZMGlu1) beta-glucosidase and a model of its complex with p-nitrophenyl beta-D-thioglucoside.

M.Czjzek, M.Cicek, V.Zamboni, W.P.Burmeister, D.R.Bevan, B.Henrissat, A.Esen.

ABSTRACT

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.