Strategies to reduce end-product inhibition in family 48 glycoside hydrolases

Proteins. 2016 Mar;84(3):295-304. doi: 10.1002/prot.24965. Epub 2016 Feb 1.

Abstract

Family 48 cellobiohydrolases are some of the most abundant glycoside hydrolases in nature. They are able to degrade cellulosic biomass and therefore serve as good enzyme candidates for biofuel production. Family 48 cellulases hydrolyze cellulose chains via a processive mechanism, and produce end products composed primarily of cellobiose as well as other cellooligomers (dp ≤ 4). The challenge of utilizing cellulases in biofuel production lies in their extremely slow turnover rate. A factor contributing to the low enzyme activity is suggested to be product binding to enzyme and the resulting performance inhibition. In this study, we quantitatively evaluated the product inhibitory effect of four family 48 glycoside hydrolases using molecular dynamics simulations and product expulsion free-energy calculations. We also suggested a series of single mutants of the four family 48 glycoside hydrolases with theoretically reduced level of product inhibition. The theoretical calculations provide a guide for future experimental studies designed to produce mutant cellulases with enhanced activity.

Keywords: biofuels; cellulose; glycoside hydrolases; molecular dynamics; product inhibition.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Substitution
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Catalytic Domain
  • Enzyme Inhibitors / chemistry
  • Glycoside Hydrolases / chemistry*
  • Glycoside Hydrolases / genetics
  • Molecular Dynamics Simulation
  • Protein Structure, Secondary
  • Structural Homology, Protein
  • Thermodynamics

Substances

  • Bacterial Proteins
  • Enzyme Inhibitors
  • Glycoside Hydrolases