Proline-poor hydrophobic domains modulate the assembly and material properties of polymeric elastin.
Elastin is a self-assembling extracellular matrix protein that provides elasticity to tissues. For entropic elastomers such as elastin, conformational disorder of the monomer building block, even in the polymeric form, is essential for elastomeric recoil. The highly hydrophobic monomer employs a range of strategies for maintaining disorder and flexibility within hydrophobic domains, particularly involving a minimum compositional threshold of proline and glycine residues. However, the native sequence of hydrophobic elastin domain 30 is uncharacteristically proline-poor and, as an isolated polypeptide, is susceptible to formation of amyloid-like structures comprised of stacked β-sheet. Here we investigated the biophysical and mechanical properties of multiple sets of elastin-like polypeptides designed with different numbers of proline-poor domain 30 from human or rat tropoelastins. We compared the contributions of these proline-poor hydrophobic sequences to self-assembly through characterization of phase separation, and to the tensile properties of cross-linked, polymeric materials. We demonstrate that length of hydrophobic domains and propensity to form β-structure, both affecting polypeptide chain flexibility and cross-link density, play key roles in modulating elastin mechanical properties. This study advances the understanding of elastin sequence-structure-function relationships, and provides new insights that will directly support rational approaches to the design of biomaterials with defined suites of mechanical properties.
Molecular Structure and Function Program, Research Institute, Hospital For Sick Children, 555 University Ave, Toronto, ON, M5G1X8, Canada.
Lisa D
LD
Muiznieks
Molecular Structure and Function Program, Research Institute, Hospital For Sick Children, 555 University Ave, Toronto, ON, M5G1X8, Canada.
Sean E
SE
Reichheld
Molecular Structure and Function Program, Research Institute, Hospital For Sick Children, 555 University Ave, Toronto, ON, M5G1X8, Canada.
Eva E
EE
Sitarz
Molecular Structure and Function Program, Research Institute, Hospital For Sick Children, 555 University Ave, Toronto, ON, M5G1X8, Canada.
Ming
M
Miao
Molecular Structure and Function Program, Research Institute, Hospital For Sick Children, 555 University Ave, Toronto, ON, M5G1X8, Canada.|Department of Biochemistry, University of Toronto, Toronto, ON, M5S1A8, Canada.|Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5S1A8, Canada.
Fred W
FW
Keeley
D004549:Elastin / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D011108:Polymers / Q000737:chemistry*; D011392:Proline / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary
D011108:Polymers; D004549:Elastin; D011392:Proline
conformational disorder; elastin; entropic elasticity; proline; β-sheet