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Ligand binding induces enhanced conformational exchange in xylanase B2 from Streptomyces lividans

Gagné, Donald; Nguyen-Thi, Nhung; Narayanan, Chitra; Roux, Louise D.; Brunzelle, Joseph S.; Couture, Jean-François; Agarwal, Pratul K; Doucet, Nicolas . Ligand binding induces enhanced conformational exchange in xylanase B2 from Streptomyces lividans In: 16e Symposium annuel de PROTEO, 13 Mai 2016, Université Laval, Québec, QC.

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Résumé

Xylanases catalyze the hydrolysis of xylan, an abundant carbon and energy source with important commercial ramifications. Despite tremendous efforts devoted to the catalytic improvement of xylanases, success remains limited due to relatively poor under standing of their molecular properties. Previous reports suggested the potential role of at omic-scale residue dynamics in modulating the catalytic activity of GH11 xylanases; however, d ynamics in these studies was probed on timescales orders of magnitude faster than the cataly tic time frame. Here, we used NMR titration, chemical shift projection analysis (CHESPA) and relaxation dispersion experiments ( 15 N-CPMG) in combination with computational simulations to probe conformational motions occurring on the catalytically relevant millisecond time frame in xylanase B2 (XlnB2) and its catalytically impaired mutant E87A from Streptomyces lividans 6 6. Our results show distinct dynamical properties for the apo and ligand-bound states of the enzymes. The apo form of XlnB2 experiences conformational exchange for residues in the fingers and palm regions of the catalytic cleft while the catalytically impaired E87A variant only displa ys millisecond dynamics in the fingers, demonstrating the long-range effect of mutation on flexibility. Ligand binding induces enhanced conformational exchange of residues interacting with the ligand in the fingers and thumb loop regions, emphasizing the potential role of residue motions in t he fingers and thumb loop regions for recognition, positioning, and/or stabilization of ligands i n XlnB2. To the best of our knowledge, this work represents the first experimental characterization of millisecond dynamics in a GH11 xylanase family member. These results offer new insights into t he potential role of conformational exchange in GH11 xylanases, providing essential dynamic informa tion to help improve protein engineering and design applications.

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Centre: Centre INRS-Institut Armand Frappier
Date de dépôt: 13 mars 2019 15:28
Dernière modification: 13 mars 2019 15:28
URI: http://espace.inrs.ca/id/eprint/5802

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