7D6A image
Entry Detail
PDB ID:
7D6A
Keywords:
Title:
Crystal structure of Oryza sativa Os4BGlu18 monolignol beta-glucosidase
Biological Source:
Host Organism:
PDB Version:
Deposition Date:
2020-09-29
Release Date:
2021-01-13
Method Details:
Experimental Method:
Resolution:
1.70 Å
R-Value Free:
0.17
R-Value Work:
0.15
R-Value Observed:
0.15
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Beta-glucosidase 18
Chain IDs:A, B
Chain Length:482
Number of Molecules:2
Biological Source:Oryza sativa subsp. japonica
Primary Citation
Structural analysis of rice Os4BGlu18 monolignol beta-glucosidase.
Plos One 16 e0241325 e0241325 (2021)
PMID: 33471829 DOI: 10.1371/journal.pone.0241325

Abstact

Monolignol glucosides are storage forms of monolignols, which are polymerized to lignin to strengthen plant cell walls. The conversion of monolignol glucosides to monolignols is catalyzed by monolignol β-glucosidases. Rice Os4BGlu18 β-glucosidase catalyzes hydrolysis of the monolignol glucosides, coniferin, syringin, and p-coumaryl alcohol glucoside more efficiently than other natural substrates. To understand more clearly the basis for substrate specificity of a monolignol β-glucosidase, the structure of Os4BGlu18 was determined by X-ray crystallography. Crystals of Os4BGlu18 and its complex with δ-gluconolactone diffracted to 1.7 and 2.1 Å resolution, respectively. Two protein molecules were found in the asymmetric unit of the P212121 space group of their isomorphous crystals. The Os4BGlu18 structure exhibited the typical (β/α)8 TIM barrel of glycoside hydrolase family 1 (GH1), but the four variable loops and two disulfide bonds appeared significantly different from other known structures of GH1 β-glucosidases. Molecular docking studies of the Os4BGlu18 structure with monolignol substrate ligands placed the glycone in a similar position to the δ-gluconolactone in the complex structure and revealed the interactions between protein and ligands. Molecular docking, multiple sequence alignment, and homology modeling identified amino acid residues at the aglycone-binding site involved in substrate specificity for monolignol β-glucosides. Thus, the structural basis of substrate recognition and hydrolysis by monolignol β-glucosidases was elucidated.

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