Open AccessThe role of conserved tryptophan residues in the interaction of a bacterial cellulose binding domain with its ligand
Author(s) -
Poole Debbie M.,
Hazlewood Geoffrey P.,
Huskisson Neville S.,
Virden Richard,
Gilbert Harry J.
Publication year - 1993
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1993.tb05938.x
Subject(s) - tryptophan , cellulose , biochemistry , alanine , chemistry , ligand (biochemistry) , binding site , pseudomonas fluorescens , stereochemistry , amino acid , biology , bacteria , receptor , genetics
The five conserved tryptophan residues in the cellulose binding domain of xylanase A from Pseudomonas fluorescens subsp. cellulosa were replaced with alanine and phenylalanine. The mutated domains were fused to mature alkaline phosphatase, and the capacity of the hybrid proteins to bind cellulose was assessed. Alanine substitution of the tryptophan residues, in general, resulted in a significant decrease in the capacity of the cellulose binding domains to bind cellulose. Mutant domains containing phenylalanine substitution retained some affinity for cellulose. The C‐terminal proximal tryptophan did not play an important role in ligand binding, while Trp 13 , Trp 34 and Trp 38 were essential for the cellulose binding domain to retain cellulose binding capacity. Data presented in this study suggest major differences in the mechanism of cellulose attachment between Pseudomonas and Cellulomonas cellulose binding domains.