title: Re- or displacement of invariant residues in the C-terminal half of the catalytic domain strongly affects catalysis by glucosyltransferase R.
abstract: It is shown that exchanges of single invariant amino acids in two C-terminal catalytic domain segments of the glucosyltransferase R (GtfR) strongly affect its catalytic properties. Drastic decreases of activity through re- or displacements of Tyr965 demonstrate a crucial role of this residue. Similarly, exchanges of amino acids Asp1004, Val1006, and Tyr1011 profoundly influenced catalytic parameters. These results are interpreted on the basis of a homology model of the catalytic domain. They are consistent with the view that Tyr965 is a constituent of the substrate-binding pocket and directly contacts the sucrose molecule, whereas the other critical residues contribute to the required positioning of Tyr965 and other active site residues.
authors.affiliation: Division of Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Wittrock
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Swistowska
authors.forename: Wera
authors.initials: W
authors.lastname: Collisi
authors.forename: Birgit
authors.initials: B
authors.lastname: Hofmann
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Hecht
authors.forename: Bernd
authors.initials: B
authors.lastname: Hofer
mesh_terms: D002384:Catalysis; D020134:Catalytic Domain; D016695:Glycosyltransferases / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular
chemical_list: D016695:Glycosyltransferases