An outcome-defining role for the triple-helical domain in regulating collagen-I assembly.

Autor:	Yammine KM; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA., Li RC; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA., Borgula IM; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA., Mirda Abularach S; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA., DiChiara AS; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA., Raines RT; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA.; Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA.; Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA., Shoulders MD; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA.; Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA.; Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA.
Jazyk:	angličtina
Zdroj:	Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2024 Nov 12; Vol. 121 (46), pp. e2412948121. Date of Electronic Publication: 2024 Nov 06.
DOI:	10.1073/pnas.2412948121
Abstrakt:	Collagens are the foundational component of diverse tissues, including skin, bone, cartilage, and basement membranes, and are the most abundant protein class in animals. The fibrillar collagens are large, complex, multidomain proteins, all containing the characteristic triple helix motif. The most prevalent collagens are heterotrimeric, meaning that cells express at least two distinctive procollagen polypeptides that must assemble into specific heterotrimer compositions. The molecular mechanisms ensuring correct heterotrimeric assemblies are poorly understood - even for the most common collagen, type-I. The longstanding paradigm is that assembly is controlled entirely by the ~30 kDa globular C-propeptide (C-Pro) domain. Still, this dominating model for procollagen assembly has left many questions unanswered. Here, we show that the C-Pro paradigm is incomplete. In addition to the critical role of the C-Pro domain in templating assembly, we find that the amino acid sequence near the C terminus of procollagen's triple-helical domain plays an essential role in defining procollagen assembly outcomes. These sequences near the C terminus of the triple-helical domain encode conformationally stabilizing features that ensure only desirable C-Pro-mediated trimeric templates are committed to irreversible triple-helix folding. Incorrect C-Pro trimer assemblies avoid commitment to triple-helix formation thanks to destabilizing features in the amino acid sequences of their triple helix. Incorrect C-Pro assemblies are consequently able to dissociate and search for new binding partners. These findings provide a distinctive perspective on the mechanism of procollagen assembly, revealing the molecular basis by which incorrect homotrimer assemblies are avoided and setting the stage for a deeper understanding of the biogenesis of this ubiquitous protein. Competing Interests: Competing interests statement:The authors declare no competing interest.
Databáze:	MEDLINE
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