Molecular basis of elastic fiber formation. Critical interactions and a tropoelastin-fibrillin-1 cross-link.
We have investigated the molecular basis of elastic fiber formation on fibrillin microfibrils. Binding assays revealed high affinity calcium-independent binding of two overlapping fibrillin-1 fragments (encoded by central exons 18-25 and 24-30) to tropoelastin, which, in microfibrils, map to an exposed "arms" feature adjacent to the beads. A further binding site within an adjacent fragment (encoded by exons 9-17) was within an eight-cysteine motif designated TB2 (encoded by exons 16 and 17). Binding to TB2 was ablated by the presence of N-terminal domains (encoded by exons 1-8) and reduced after deleting the proline-rich region. A novel transglutaminase cross-link between tropoelastin and fibrillin-1 fragment (encoded by exons 9-17) was localized by mass spectrometry to a sequence encoded by exon 17. The high affinity binding and cross-linking of tropoelastin to a central fibrillin-1 sequence confirm that this association is fundamental to elastic fiber formation. Microfibril-associated glycoprotein-1 showed calcium-dependent binding of moderate affinity to fibrillin-1 N-terminal fragment (encoded by exons 1-8), which localize to the beads. Microfibril-associated glycoprotein-1 thus contributes to microfibril organization but may also form secondary interactions with adjacent microfibril-bound tropoelastin.
Rock
Matthew J
MJ
Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, University of Manchester, 2.205 Stopford Building, Oxford Road, Manchester M13 9PT, United Kingdom.
Cain
Stuart A
SA
Freeman
Lyle J
LJ
Morgan
Amanda
A
Mellody
Kieran
K
Marson
Andrew
A
Shuttleworth
C Adrian
CA
Weiss
Anthony S
AS
Kielty
Cay M
CM
D000595:Amino Acid Sequence; D001665:Binding Sites; D003285:Contractile Proteins / Q000737:chemistry / Q000378:metabolism; D003432:Cross-Linking Reagents; D004547:Elastic Tissue / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000737:chemistry / Q000378:metabolism; D000071838:Fibrillin-1; D000071837:Fibrillins; D006801:Humans; D020894:Microfibrils / Q000737:chemistry / Q000378:metabolism; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D000072260:RNA Splicing Factors; D011994:Recombinant Proteins; D014333:Tropoelastin / Q000737:chemistry / Q000378:metabolism*; D054392:Adipokines
D003285:Contractile Proteins; D003432:Cross-Linking Reagents; D016326:Extracellular Matrix Proteins; D000071838:Fibrillin-1; D000071837:Fibrillins; D008840:Microfilament Proteins; D000072260:RNA Splicing Factors; D011994:Recombinant Proteins; D014333:Tropoelastin; C000605722:FBN1 protein, human; D054392:Adipokines; C016598:microfibrillar protein