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All three surface tryptophans in Type IIa cellulose binding domains play a pivotal role in binding both soluble and insoluble ligands
Author(s) -
Nagy Tibor,
Simpson Peter,
Williamson Michael P.,
Hazlewood Geoffrey P.,
Gilbert Harry J.,
Orosz Laszlo
Publication year - 1998
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/s0014-5793(98)00625-5
Subject(s) - mutant , cellulose , biochemistry , wild type , chemistry , binding domain , binding site , stereochemistry , gene
The three surface tryptophans of the Type IIa cellulose binding domain of Pseudomonas fluorescens subsp. cellulosa xylanase A (CBD XYLA ) were independently mutated to alanine, to create the mutants W13A, W49A and W66A. The three mutant proteins were purified, and their capacity to bind to a variety of ligands was determined. The mutant proteins have native‐like structures but exhibited much weaker affinity for crystalline and amorphous cellulose and for cellohexaose than the wild type. These data indicate that all three tryptophans are important for binding to cellulose, and support a model in which the three tryptophans form an aromatic strip on the surface of the protein that binds to a single cellulose.