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- Title
Identification of structural determinants for substrate binding and turnover by glucosyltransferase R supports the permutation hypothesis
- Authors
Swistowska, Anna Maria; Gronert, Sabine; Wittrock, Sabine; Collisi, Wera; Hecht, Hans-Jürgen; Hofer, Bernd
- Abstract
Abstract: 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.
- Subjects
SUCROSE; SUGARS; FOOD; SUGARCANE products
- Publication
FEBS Letters, 2007, Vol 581, Issue 21, p4036
- ISSN
0014-5793
- Publication type
Article
- DOI
10.1016/j.febslet.2007.07.031