Proline provides site-specific flexibility for in vivo collagen
Wing Ying Chow1,2, Chris J Forman1,3, Dominique Bihan4,5
1Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
Scientific Reports
|September 16, 2018
Summary
Proline residues in collagen triplets act as flexible "expansion joints," maintaining tissue strength and cell binding sites. This discovery explains how collagen provides both flexibility and structural integrity in tissues.
Area of Science:
- Biochemistry
- Biophysics
- Materials Science
Background:
- Fibrillar collagens are crucial for tissue mechanical strength and cell interactions.
- Maintaining tissue flexibility while preserving specific cell-binding sites is a key challenge.
Purpose of the Study:
- To investigate the role of proline residues in collagen structure and function.
- To understand how collagen achieves both flexibility and well-defined ligand binding sites.
Main Methods:
- Utilized two-dimensional 13C-13C correlation NMR spectroscopy.
- Analyzed 13C-labeled intact ex vivo bone and in vitro osteoblast extracellular matrix.
Main Results:
- Identified glycine-proline-hydroxyproline (Gly-Pro-Hyp) triplets as key to local conformational flexibility.
- Observed high conservation of Gly-Pro-Hyp triplet positions across species.
- Found Gly-Pro-Hyp triplets spatially clustered in collagen type I fibril models.
Conclusions:
- Gly-Pro-Hyp triplets function as 'expansion joints' in collagen fibrils.
- These triplets maintain molecular ordering and preserve the integrity of ligand binding sites.
- This mechanism explains collagen's ability to provide tissue flexibility and biological function.
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