Conserved sequence motifs in levansucrases and bifunctional beta-xylosidases and alpha-L-arabinases

Comparison of the amino acid sequences of two families of glycosyl hydrolas es reveals that they are related in a region in the central part of the seq uences, One of these families (GH family 68) includes levansucrases acid th e other one (glycosyl hydrolase family 43) includes bifunctional beta-xylos idases and alpha-L-arabinofuranosidases. The similarity of the primary stru cture of proteins from these families allows us to consider the invariant g lutamate residue as a component of their active center. It is shown for the first time that glycosyl hydrolases recognizing different glycofuranoside residues can have a common sequence motif. (C) 1999 Federation of European Biochemical Societies.