Probing the dynamics between the substrate and the product towards glucose tolerance of Halothermothrix orenii β-glucosidase

Thermal Sensitivity of the Enzymatic Activity of β-Glucosidase: Simulations Lend Mechanistic Insights into Experimental Observations

“…Favorable interactions of p NPGlc with Glu225 at the gatekeeper region may facilitate its entry toward the catalytic site and enable higher binding and catalytic efficiency of BglB toward p NPGlc. The role of gatekeeper residues in substrate accessibility has been reported earlier as well. ,− Overall, the catalytic site residues (Glu356 and Glu167) show the most favorable interactions, whereas most aglycone residues showed largely unfavorable interactions except for Asn223, which is a highly conserved residue found in immediate proximity of the catalytic site (Table S4). While the importance of these residues in substrate binding stability with temperature could be observed, a definitive conclusion of their contribution to protein stability and how mutating these individual residues would affect the network of intraprotein interactions or protein–substrate interactions will require further investigation.…”

“…Figure 7. (a) A cross-section (generated by Chimera 1.16)64 of the active site pocket to highlight the location of residues reported via MM-GBSA analysis. The inset describes the subsites of the pocket: the glycone binding site (−1, in green), the catalytic site (in red), the aglycone binding site (+1, in yellow), and the gatekeeper residues (+2, in magenta).…”

Molecular Insight into Glucose-Induced Conformational Change to Investigate Uncompetitive Inhibition of GH1 β-Glucosidase

“…14 In another study, MD simulation of the same BG was performed in the presence of both the p-nitrophenyl-β-D-glucopyranoside substrate and glucose product that unveiled the concentrationdependent role of glucose as both a stimulator and inhibitor of the enzyme. 15 H0HC94 from the bacteria A. tumefaciens 5A was observed to be moderately glucose-tolerant GH1 BG. 4 In that study, the enzymatic activity (k cat ) decreased from 277.93 s −1 in 0 M glucose to 236.71 s −1 (0.1 M glucose) and 120.31 s −1 (0.8 M glucose).…”

“…orenii revealed that the widened active site tunnel due to the building up of glucose at the catalytic site blocked the substrate accessibility and in turn inhibited the enzymatic activity . In another study, MD simulation of the same BG was performed in the presence of both the p -nitrophenyl-β- d -glucopyranoside substrate and glucose product that unveiled the concentration-dependent role of glucose as both a stimulator and inhibitor of the enzyme …”

Role of Conformational Change and Glucose Binding Sites in the Enhanced Glucose Tolerance of Agrobacterium tumefaciens 5A GH1 β-Glucosidase Mutants

“…However, most β-glucosidases are prone to glucose inhibition, and the consequent accumulation further inhibits cellobiohydrolase and endoglucanase to result in inefficient biomass hydrolysis. Therefore, the identification of efficient β-glucosidases has been an ongoing effort. − Recently, there were reports of glucose-tolerant GH1 β-glucosidase that can tolerate very high glucose concentrations. ,,− Glucose tolerance has been linked to stimulatory effects by low concentration of glucose, transglycosylation, allosteric effects, , and nonproductive substrate binding . The higher glucose-tolerant enzymes thus far are all reported from the GH1 family.…”