Molecular insights of a xyloglucan endo-transglycosylase/hydrolase of radiata pine (PrXTH1) expressed in response to inclination: Kinetics and computational study

• Published in: Plant physiology and biochemistry 2019-03, Vol.136, p.155-161
• Main Authors: Morales-Quintana, Luis, Carrasco-Orellana, Cristian, Beltrán, Dina, Moya-León, María Alejandra, Herrera, Raúl
• Format: Article
• Language: English
• Subjects: Cell Wall - metabolism; Cloning, Molecular; Enzymatic parameters; Gene Expression Regulation, Plant - physiology; Glycosyltransferases - metabolism; Glycosyltransferases - physiology; Kinetics; Molecular Docking Simulation; Pichia - enzymology; Pichia - metabolism; Pichia - physiology; Plant cell wall; Plant Proteins - metabolism; Plant Proteins - physiology; Recombinant Proteins; Substrate Specificity; Xyloglucan endotransglycosylase/hydrolases; Xyloglycans
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2019.01.016

Xyloglucan endotransglycosylase/hydrolases (XTH) may have endotransglycosylase (XET) and/or hydrolase (XEH) activities. Previous studies confirmed XET activity for PrXTH1 protein from radiata pine. XTHs could interact with many hemicellulose substrates, but the favorite substrate of PrXTH1 is still unknown. The prediction of union type and energy stability of the complexes formed between PrXTH1 and different substrates (XXXGXXXG, XXFGXXFG, XLFGXLFG and cellulose) were determined using bioinformatics tools. Molecular Docking, Molecular Dynamics, MM-GBSA and Electrostatic Potential Calculations were employed to predict the binding modes, free energies of interaction and the distribution of electrostatic charge. The results suggest that the enzyme formed more stable complexes with hemicellulose substrates than cellulose, and the best ligand was the xyloglucan XLFGXLFG (free energy of −58.83 ± 0.8 kcal mol−1). During molecular dynamics trajectories, hemicellulose fibers showed greater stability than cellulose. Aditionally, the kinetic properties of PrXTH1 enzyme were determined. The recombinant protein was active and showed an optimal pH 5.0 and optimal temperature of 37 °C. A Km value of 20.9 mM was determined for xyloglucan oligomer. PrXTH1 is able to interact with different xyloglycans structures but no activity was observed for cellulose as substrate, remodeling cell wall structure in response to inclination. [Display omitted] •PrXTH1 expressed heterologous in Pichia pastoris was active.•The enzyme showed a Km value of 20.9 mM and optimal pH 5.0•Different xyloglucans structures interact with PrXTH1.•No activity was observed when cellulose was used as substrate.•Structural analysis by molecular docking correlate biochemical determinations.