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The T-knot motif revisited
F Polticelli1, S Pascarella, D Bordo
1Department of Biology, University of Rome "Tre", Italy.
Biological Chemistry
|December 14, 1999
Summary
The T-knot scaffold, a protein structure, does not require a central beta-sheet for stability. Its folding and stability depend on disulfide bonds and loop length, leading to a redefined motif.
Area of Science:
- Structural biology
- Protein science
- Biochemistry
Background:
- The T-knot scaffold is a protein structural motif characterized by two disulfide bonds forming a T-shape.
- It is found in proteins with diverse biological functions.
- Previous definitions emphasized the presence of a beta-sheet structure.
Purpose of the Study:
- To investigate the essential structural features of the T-knot scaffold.
- To determine if a central beta-sheet is required for T-knot topology.
- To propose a redefined T-knot motif based on structural analysis.
Main Methods:
- Superposition of three-dimensional structures of representative T-knot proteins.
- Analysis of common structural cores and stabilizing elements.
Main Results:
- The presence of a central beta-sheet is not essential for the T-knot topology.
- A common core formed by the two knotted disulphides, not a hydrophobic core, stabilizes the motif.
- Loop length and disulfide bond geometry are key factors for T-knot folding and stability.
Conclusions:
- The T-knot scaffold's stability is primarily governed by disulfide bond geometry and loop length, not secondary structure elements.
- A revised definition of the T-knot motif is proposed, focusing on the disulfide knot core.