Probing the role of cation-π interaction in the thermotolerance and catalytic performance of endo-polygalacturonases

Abstract

Understanding the dynamics of the key pectinase, polygalacturonase, and improving its thermotolerance and catalytic efficiency are of importance for the cost-competitive bioconversion of pectic materials. By combining structure analysis and molecular dynamics (MD) simulations, eight mutagenesis sites having the potential to form cation-π interactions were identified in the widely used fungal endo-polygalacturonase PG63. In comparison to the wild-type, three single mutants H58Y, T71Y and T304Y showed improved thermostability (the apparent Tms increased by 0.6−3.9 °C) and catalytic efficiency (by up to 32-fold). Chromatogram analysis of the hydrolysis products indicated that a larger amount of shorter sugars were released from the polygalacturonic acid by these three mutants than by the wild-type. MD analysis of the enzyme-substrate complexes illustrated that the mutants with introduced cation-π interaction have modified conformations of catalytic crevice, which provide an enviable environment for the catalytic process. Moreover, the lower plasticity of T3 loop 2 at the edge of the subsite tunnel appears to recruit the reducing ends of oligogalacturonide into the active site tunnel and initiates new hydrolysis reactions. This study demonstrates the importance of cation-π interaction in protein conformation and provides a realistic strategy to enhance the thermotolerance and catalytic performance of endo-polygalacturonases.

Different-ligand and different-metal xylaratogermanates as effectors of Penicillium restrictum IMV F-100139 α-L-rhamnosidase and α-galactosidase

“…The data obtained on the basis of UV spectra of P. restrictum α-L-rhamnosidase indicate a significant contribution of aromatic amino acids to both, possibly, the topology of the active center, and the thermal stabilization of the enzyme in the presence of compound (7) due to weak cation-π interactions. In recent years, studies have appeared showing the importance of cation-π interactions both for the manifestation of the catalytic properties of enzymes and for their thermal stabilization [19]. There is evidence that, in mesophiles, Phe residues play a key role in the cation-π interaction, while for thermophiles Tyr has a greater effect [20].…”

Binding of Alkali Metal Ions with 1,3,5-Tri(phenyl)benzene and 1,3,5-Tri(naphthyl)benzene: The Effect of Phenyl and Naphthyl Ring Substitution on Cation−π Interactions Revealed by DFT Study

“…The structure α,α,α-TNB (3) is about 8 and 5 kcal/mol less stable than β,β,β-TNB (6) at the B3LYP/def2-QZVP and M06-2X/ def2-QZVP levels, respectively. The peri-repulsion plays a key factor for higher relative energy of α,α,α-TNB (3) compared to β,β,β-TNB (6). Previously, the experimental study has reported the attractive and repulsive effects in the interactions of different functional groups in peri-disubstituted naphthalene.…”

“…Cation−π interaction is now well recognized by the chemical and biological sciences community as an important contributor of nonbonding interactions in macromolecular structures, drug–receptor interactions, protein–protein interactions, and neurobiology. − It plays an important role in catalysis, , protein structure determination, − and molecular recognition processes within ion channels and enzymes. − In-depth knowledge on the cation−π interactions will certainly benefit environmental science and mineral surface chemistry . Cation−π interactions mainly include electrostatic, inductive, and charge transfer effects .…”

Cysteine Engineering of an Endo-polygalacturonase from Talaromyces leycettanus JCM 12802 to Improve Its Thermostability

“…The enzyme shares a parallel β-helix structure. Factors related to improved thermostability of enzymes include hydrophobic interactions, hydrogen bonds, , salt bridges, , cation−π bond interactions, aromatic ring interactions, , and disulfide bonds . There are four highly conserved disulfide bonds in PG.…”