Interaction of tropoelastin with the amino-terminal domains of fibrillin-1 and fibrillin-2 suggests a role for the fibrillins in elastic fiber assembly.
Alignment of tropoelastin molecules during the process of elastogenesis is thought to require fibrillin-containing microfibrils. In this study, we have demonstrated that amino-terminal domains of two microfibrillar proteins, fibrillin-1 and fibrillin-2, interact with tropoelastin in solid phase binding assays. The tropoelastin-binding site was localized to a region beginning at the glycine-rich and proline-rich regions of fibrillin-2 and fibrillin-1, respectively, and continuing through the second 8-cysteine domain. Characterization of the binding requirements using the fibrillin-2 construct found that a folded, secondary structure was necessary for binding. Furthermore, binding between tropoelastin and fibrillin was mediated by ionic interactions involving the lysine side chains of tropoelastin. The importance of the lysine side chains was corroborated by the finding that the fibrillin-2 construct did not bind to mature elastin, whose lysine side chains have been modified to form cross-links. Interestingly, there was no interaction between the fibrillin constructs and tropoelastin in solution phase, suggesting that binding of tropoelastin to a solid substrate exposes a cryptic binding site. These results suggest that fibrillin plays an important role in elastic fiber assembly by binding tropoelastin and perhaps facilitating side chain alignment for efficient cross-linking.
Trask
T M
TM
Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Trask
B C
BC
Ritty
T M
TM
Abrams
W R
WR
Rosenbloom
J
J
Mecham
R P
RP
D000595:Amino Acid Sequence; D000906:Antibodies; D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D004548:Elasticity; D016326:Extracellular Matrix Proteins / Q000737:chemistry / Q000378:metabolism; D000071838:Fibrillin-1; D000071840:Fibrillin-2; D000071837:Fibrillins; D006031:Glycosylation; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D014333:Tropoelastin / Q000737:chemistry* / Q000378:metabolism; D054392:Adipokines
D000906:Antibodies; D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D000071838:Fibrillin-1; D000071840:Fibrillin-2; D000071837:Fibrillins; D008840:Microfilament Proteins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D014333:Tropoelastin; C000605722:FBN1 protein, human; D054392:Adipokines; C000605723:FBN2 protein, human