Re- or displacement of invariant residues in the C-terminal half of the catalytic domain strongly affects catalysis by glucosyltransferase R.
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.
Wittrock
Sabine
S
Division of Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany.
Swistowska
Anna Maria
AM
Collisi
Wera
W
Hofmann
Birgit
B
Hecht
Hans-Jürgen
HJ
Hofer
Bernd
B
D002384:Catalysis; D020134:Catalytic Domain; D016695:Glycosyltransferases / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular
D016695:Glycosyltransferases