Vascular Ehlers-Danlos syndrome mutations in type III collagen differently stall the triple helical folding.

Mizuno K, Boudko S, Engel J, Bächinger HP
J Biol Chem. 2013 288 (26): 19166-76

PMID: 23645670 · PMCID: PMC3696688 · DOI:10.1074/jbc.M113.462002

Vascular Ehlers-Danlos syndrome (EDS) type IV is the most severe form of EDS. In many cases the disease is caused by a point mutation of Gly in type III collagen. A slower folding of the collagen helix is a potential cause for over-modifications. However, little is known about the rate of folding of type III collagen in patients with EDS. To understand the molecular mechanism of the effect of mutations, a system was developed for bacterial production of homotrimeric model polypeptides. The C-terminal quarter, 252 residues, of the natural human type III collagen was attached to (GPP)7 with the type XIX collagen trimerization domain (NC2). The natural collagen domain forms a triple helical structure without 4-hydroxylation of proline at a low temperature. At 33 °C, the natural collagenous part is denatured, but the C-terminal (GPP)7-NC2 remains intact. Switching to a low temperature triggers the folding of the type III collagen domain in a zipper-like fashion that resembles the natural process. We used this system for the two known EDS mutations (Gly-to-Val) in the middle at Gly-910 and at the C terminus at Gly-1018. In addition, wild-type and Gly-to-Ala mutants were made. The mutations significantly slow down the overall rate of triple helix formation. The effect of the Gly-to-Val mutation is much more severe compared with Gly-to-Ala. This is the first report on the folding of collagen with EDS mutations, which demonstrates local delays in the triple helix propagation around the mutated residue.

MeSH Terms (15)

Circular Dichroism Collagen Collagen Type III Ehlers-Danlos Syndrome Humans Mutation Peptidylprolyl Isomerase Point Mutation Protein Folding Protein Processing, Post-Translational Protein Structure, Secondary Protein Structure, Tertiary Recombinant Proteins Temperature Trypsin

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