RESUMEN
Collagens constitute a large family of extracellular matrix (ECM) proteins that play a fundamental role in supporting the structure of various tissues in multicellular animals. The mechanical strength of fibrillar collagens is highly dependent on the formation of covalent cross-links between individual fibrils, a process initiated by the enzymatic action of members of the lysyl oxidase (LOX) family. Fibrillar collagens are present in a wide variety of animals, therefore often being associated with metazoan evolution, where the emergence of an ancestral collagen chain has been proposed to lead to the formation of different clades. While LOX-generated collagen cross-linking metabolites have been detected in different metazoan families, there is limited information about when and how collagen acquired this particular modification. By analyzing telopeptide and helical sequences, we identified highly conserved, potential cross-linking sites throughout the metazoan tree of life. Based on this analysis, we propose that they have importantly contributed to the formation and further expansion of fibrillar collagens.
Asunto(s)
Colágeno/metabolismo , Matriz Extracelular/metabolismo , Colágenos Fibrilares/metabolismo , Proteína-Lisina 6-Oxidasa/metabolismo , Secuencia de Aminoácidos , Animales , Colágeno/clasificación , Colágeno/genética , Evolución Molecular , Colágenos Fibrilares/química , Colágenos Fibrilares/genética , Humanos , Invertebrados/genética , Invertebrados/metabolismo , Modelos Moleculares , Filogenia , Estructura Secundaria de Proteína , Homología de Secuencia de Aminoácido , Vertebrados/genética , Vertebrados/metabolismoRESUMEN
Type I collagen is the fundamental component of the extracellular matrix. Its α1 gene is the direct descendant of ancestral fibrillar collagen and contains 57 exons encoding the rod-like triple-helical COL domain. We trace the evolution of the COL domain from a primordial collagen 18 residues in length to its present 1014 residues, the limit of its possible length. In order to maintain and improve the essential structural features of collagen during evolution, exons can be added or extended only in permitted, non-random increments that preserve the position of spatially sensitive cross-linkage sites. Such sites cannot be maintained unless the twist of the triple helix is close to 30 amino acids per turn. Inspection of the gene structure of other long structural proteins, fibronectin and titin, suggests that their evolution might have been subject to similar constraints.
