Active site complementation and hexameric arrangement in the GH family 29; a structure-function study of alpha-l-fucosidase isoenzyme 1 from Paenibacillus thiaminolyticus.Kovalova, T., Koval, T., Benesova, E., Vodickova, P., Spiwok, V., Lipovova, P., Dohnalek, J.
(2019) Glycobiology 29: 59-73
- PubMed: 30544181
- DOI: 10.1093/glycob/cwy078
- PubMed Abstract:
α-l-Fucosidase isoenzyme 1 from bacterium Paenibacillus thiaminolyticus is a member of the glycoside hydrolase family GH29 capable of cleaving l-fucose from nonreducing termini of oligosaccharides and glycoconjugates. Here we present the first crysta ...
α-l-Fucosidase isoenzyme 1 from bacterium Paenibacillus thiaminolyticus is a member of the glycoside hydrolase family GH29 capable of cleaving l-fucose from nonreducing termini of oligosaccharides and glycoconjugates. Here we present the first crystal structure of this protein revealing a novel quaternary state within this family. The protein is in a unique hexameric assembly revealing the first observed case of active site complementation by a residue from an adjacent monomer in this family. Mutation of the complementing tryptophan residue caused changes in the catalytic properties including a shift of the pH optimum, a change of affinity to an artificial chromogenic substrate and a decreased reaction rate for a natural substrate. The wild-type enzyme was active on most of the tested naturally occurring oligosaccharides and capable of transglycosylation on a variety of acceptor molecules, including saccharides, alcohols or chromogenic substrates. Mutation of the complementing residue changed neither substrate specificity nor the preference for the type of transglycosylation acceptor molecule; however, the yields of the reactions were lower in both cases. Maltose molecules bound to the enzyme in the crystal structure identified surface carbohydrate-binding sites, possibly participating in binding of larger oligosaccharides.
Laboratory of Structure and Function of Biomolecules, Institute of Biotechnology of the Czech Academy of Sciences, v.v.i., Biocev, Vestec, Czech Republic.