Re- or displacement of invariant residues in the C-terminal half of the catalytic domain strongly affects catalysis by glucosyltransferase R |
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Authors: | Wittrock Sabine Swistowska Anna Maria Collisi Wera Hofmann Birgit Hecht Hans-Jürgen Hofer Bernd |
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Institution: | a Division of Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany b Department of Structural Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany c Department of Chemical Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany |
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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. |
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Keywords: | AA amino acid Fru fructose Glc glucose GTF glucosyltransferase Suc sucrose WT wild-type |
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