The mechanism of substrate (aglycone) specificity in β-glucosidases is revealed by crystal structures of mutant maize β-glucosidase-DIMBOA, -DIMBOAGlc, and -dhurrin complexes
Published in
Proceedings of the National Academy of Sciences of the United States of America, December 2000
The mechanism and the site of substrate (i.e., aglycone) recognition and specificity were investigated in maize beta-glucosidase (Glu1) by x-ray crystallography by using crystals of a catalytically inactive mutant (Glu1E191D) in complex with the natural substrate 2-O-beta-d-glucopyranosyl-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOAGlc), the free aglycone DIMBOA, and competitive inhibitor para-hydroxy-S-mandelonitrile beta-glucoside (dhurrin). The structures of these complexes and of the free enzyme were solved at 2.1-, 2.1-, 2.0-, and 2.2-A resolution, respectively. The structural data from the complexes allowed us to visualize an intact substrate, free aglycone, or a competitive inhibitor in the slot-like active site of a beta-glucosidase. These data show that the aglycone moiety of the substrate is sandwiched between W378 on one side and F198, F205, and F466 on the other. Thus, specific conformations of these four hydrophobic amino acids and the shape of the aglycone-binding site they form determine aglycone recognition and substrate specificity in Glu1. In addition to these four residues, A467 interacts with the 7-methoxy group of DIMBOA. All residues but W378 are variable among beta-glucosidases that differ in substrate specificity, supporting the conclusion that these sites are the basis of aglycone recognition and binding (i.e., substrate specificity) in beta-glucosidases. The data also provide a plausible explanation for the competitive binding of dhurrin to maize beta-glucosidases with high affinity without being hydrolyzed.
This research output has an Altmetric Attention Score of 9. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 13 May 2025.
All research outputs
#5,140,738
of 34,362,729 outputs
Outputs from Proceedings of the National Academy of Sciences of the United States of America
#48,571
of 118,929 outputs
Outputs of similar age
#12,478
of 162,323 outputs
Outputs of similar age from Proceedings of the National Academy of Sciences of the United States of America
#128
of 505 outputs
Altmetric has tracked 34,362,729 research outputs across all sources so far. Compared to these this one has done well and is in the 83rd percentile: it's in the top 25% of all research outputs ever tracked by Altmetric.
So far Altmetric has tracked 118,929 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 40.1. This one has gotten more attention than average, scoring higher than 52% of its peers.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 162,323 tracked outputs that were published within six weeks on either side of this one in any source. This one has done well, scoring higher than 87% of its contemporaries.
We're also able to compare this research output to 505 others from the same source and published within six weeks on either side of this one. This one has gotten more attention than average, scoring higher than 60% of its contemporaries.
