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Key amino acid residues for the endo‐processive activity of GH74 xyloglucanase
Author(s) -
Matsuzawa Tomohiko,
Saito Yuji,
Yaoi Katsuro
Publication year - 2014
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2014.03.023
Subject(s) - chemistry , tryptophan , biochemistry , stereochemistry , alanine , amino acid residue , amino acid , peptide sequence , gene
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.