Key amino acid residues for the endo-processive activity of GH74 xyloglucanase

FEBS Lett. 2014 May 2;588(9):1731-8. doi: 10.1016/j.febslet.2014.03.023. Epub 2014 Mar 19.

Abstract

Unlike endo-dissociative-xyloglucanases, Paenibacillus XEG74 is an endo-processive xyloglucanase that contains four unique tryptophan residues in the negative subsites (W61 and W64) and the positive subsites (W318 and W319), as indicated by three-dimensional homology modelling. Selective replacement of the positive subsite residues with alanine mutations reduced the degree of processive activity and resulted in the more endo-dissociative-activity. The results showed that W318 and W319, which are found in the positive subsites, are essential for processive degradation and are responsible for maintaining binding interactions with xyloglucan polysaccharide through a stacking effect.

Keywords: Endo-processive; Glucanase; Hemicellulose; Xyloglucan; Xyloglucanase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Amino Acid Substitution
  • Bacterial Proteins / chemistry*
  • Catalytic Domain
  • Glucans / chemistry
  • Glycoside Hydrolases / chemistry*
  • Hydrolysis
  • Kinetics
  • Models, Molecular
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Paenibacillus / enzymology*
  • Structural Homology, Protein
  • Substrate Specificity
  • Viscosity
  • Xylans / chemistry

Substances

  • Bacterial Proteins
  • Glucans
  • Xylans
  • xyloglucan
  • Glycoside Hydrolases
  • xyloglucan endo(1-4)-beta-D-glucanase