Collagen triple helix formation can be nucleated at either end.
The directional dependence of folding rates for rod-like macromolecules such as parallel alpha-helical coiled-coils, DNA double-helices, and collagen triple helices is largely unexplored. This is mainly due to technical difficulties in measuring rates in different directions. Folding of collagens is nucleated by trimeric non-collagenous domains. These are usually located at the COOH terminus, suggesting that triple helix folding proceeds from the COOH to the NH(2) terminus. Evidence is presented here that effective nucleation is possible at both ends of the collagen-like peptide (Gly-Pro-Pro)(10), using designed proteins in which this peptide is fused either NH(2)- or COOH-terminal to a nucleation domain, either T4-phage foldon or the disulfide knot of type III collagen. The location of the nucleation domain influences triple-helical stability, which might be explained by differences in the linker sequences and the presence or absence of repulsive charges at the carboxyl-terminal end of the triple helix. Triple helical folding rates are found to be independent of the site of nucleation and consistent with cis-trans isomerization being the rate-limiting step.
Frank
Sabine
S
Department of Biophysical Chemistry, Biozentrum, Universität Basel, Switzerland.
Boudko
Sergei
S
Mizuno
Kazunori
K
Schulthess
Therese
T
Engel
Jürgen
J
Bächinger
Hans Peter
HP
D000595:Amino Acid Sequence; D003094:Collagen / Q000737:chemistry*; D007700:Kinetics; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000378:metabolism; D014461:Ultracentrifugation
D011994:Recombinant Proteins; D003094:Collagen