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Identification of structural determinants for substrate binding and turnover by glucosyltransferase R supports the permutation hypothesis
Author(s) -
Swistowska Anna Maria,
Gronert Sabine,
Wittrock Sabine,
Collisi Wera,
Hecht Hans-Jürgen,
Hofer Bernd
Publication year - 2007
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.2007.07.031
Subject(s) - glucosyltransferases , glucosyltransferase , trimer , biochemistry , permutation (music) , chemistry , stereochemistry , biology , enzyme , dimer , organic chemistry , physics , acoustics
Segments that may crucially influence the catalytic behaviour of glucosyltransferases of the glucansucrase type were selected for modification. This was done by sequence alignments, followed by structural modelling of the putative catalytic domain, based on a permuted form of the glucosyltransferase R (GtfR) of Streptococcus oralis . Five selected regions, located in the C‐terminal half of the potential catalytic domain, were replaced by segments found at equivalent positions in other glucosyltransferases. The exchanges of four of these regions significantly affected catalysis by GtfR. This identified C‐terminal determinants for substrate binding and turnover and supports the so‐called permutation hypothesis with respect to enzymes of the glucansucrase type. Based on the model, roles are proposed for specific residues. Major effects appear to involve a re‐positioning of the C‐terminal Tyr965 that very likely serves as a hydrophobic platform for the substrate.