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Re‐ or displacement of invariant residues in the C‐terminal half of the catalytic domain strongly affects catalysis by glucosyltransferase R
Author(s) -
Wittrock Sabine,
Swistowska Anna Maria,
Collisi Wera,
Hofmann Birgit,
Hecht Hans-Jürgen,
Hofer Bernd
Publication year - 2008
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.12.040
Subject(s) - glucosyltransferase , catalysis , residue (chemistry) , chemistry , stereochemistry , homology (biology) , amino acid , invariant (physics) , biophysics , biochemistry , biology , enzyme , physics , mathematical physics
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.