title: Structural determinants of cross-linking and hydrophobic domains for self-assembly of elastin-like polypeptides.
abstract: Elastin is a major structural protein found in large blood vessels, lung, ligaments, and skin, imparting the physical properties of extensibility and elastic recoil to these tissues. To achieve the required structural durability of the elastic matrix, the elastin monomer, tropoelastin, undergoes ordered assembly into a covalently cross-linked, fibrillar polymeric structure. Human tropoelastin consists of 34 exons coding for alternating hydrophobic and cross-linking domains. Using a series of well-defined recombinant polypeptides based on human elastin sequences mimicking native elastin, we have previously investigated the role of sequence and context of hydrophobic domains in elastin self-assembly. Here, we demonstrate that the structure of both cross-linking and hydrophobic domains have significant effects on the assembly of these polypeptides. Removing a putative flexible hinge region in the center of a cross-linking domain substantially increased the alpha-helical content and strongly promoted their self-aggregation. However, while trifluoroethanol (TFE) promoted and urea inhibited self-assembly of these polypeptides, these effects were not predominantly due to altered alpha-helicity of the polypeptides. Our results suggest that, while increased alpha helicity also favors this process, the major effect of TFE to promote organized self-assembly of elastin-like polypeptides is likely related to direct effects of this cosolvent on hydrophobic domains. Such simple elastin polypeptide models can provide an important tool for understanding the relationships between sequence, structure, and polymeric assembly of elastin.
authors.affiliation: Research Institute, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada.
authors.forename: Ming
authors.initials: M
authors.lastname: Miao
authors.forename: Judith T
authors.initials: JT
authors.lastname: Cirulis
authors.forename: Shaun
authors.initials: S
authors.lastname: Lee
authors.forename: Fred W
authors.initials: FW
authors.lastname: Keeley
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004547:Elastic Tissue / Q000737:chemistry / Q000378:metabolism; D004549:Elastin / Q000737:chemistry* / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008969:Molecular Sequence Data; D009154:Mutation; D009842:Oligopeptides / Q000737:chemistry* / Q000235:genetics; D017433:Protein Structure, Secondary; D013696:Temperature; D014270:Trifluoroethanol / Q000494:pharmacology; D014333:Tropoelastin / Q000737:chemistry / Q000235:genetics; D014508:Urea / Q000494:pharmacology
chemical_list: D003432:Cross-Linking Reagents; D009842:Oligopeptides; D014333:Tropoelastin; D014270:Trifluoroethanol; D014508:Urea; D004549:Elastin