Tropoelastin bridge region positions the cell-interactive C terminus and contributes to elastic fiber assembly.
The tropoelastin monomer undergoes stages of association by coacervation, deposition onto microfibrils, and cross-linking to form elastic fibers. Tropoelastin consists of an elastic N-terminal coil region and a cell-interactive C-terminal foot region linked together by a highly exposed bridge region. The bridge region is conveniently positioned to modulate elastic fiber assembly through association by coacervation and its proximity to dominant cross-linking domains. Tropoelastin constructs that either modify or remove the entire bridge and downstream regions were assessed for elastogenesis. These constructs focused on a single alanine substitution (R515A) and a truncation (M155n) at the highly conserved arginine 515 site that borders the bridge. Each form displayed less efficient coacervation, impaired hydrogel formation, and decreased dermal fibroblast attachment compared to wild-type tropoelastin. The R515A mutant protein additionally showed reduced elastic fiber formation upon addition to human retinal pigmented epithelium cells and dermal fibroblasts. The small-angle X-ray scattering nanostructure of the R515A mutant protein revealed greater conformational flexibility around the bridge and C-terminal regions. This increased flexibility of the R515A mutant suggests that the tropoelastin R515 residue stabilizes the structure of the bridge region, which is critical for elastic fiber assembly.
School of Molecular Bioscience, University of Sydney, New South Wales 2006, Australia.
Giselle C
GC
Yeo
Clair
C
Baldock
Anne
A
Tuukkanen
Manfred
M
Roessle
Leanne B
LB
Dyksterhuis
Steven G
SG
Wise
Jacqueline
J
Matthews
Suzanne M
SM
Mithieux
Anthony S
AS
Weiss
D002448:Cell Adhesion; D002450:Cell Communication; D002478:Cells, Cultured; D004547:Elastic Tissue / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D006801:Humans; D020100:Hydrogels; D018613:Microscopy, Confocal; D008958:Models, Molecular; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D010316:Particle Size; D017434:Protein Structure, Tertiary; D059748:Proteolysis; D012996:Solutions; D013329:Structure-Activity Relationship; D013696:Temperature; D014333:Tropoelastin / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure
D020100:Hydrogels; D050505:Mutant Proteins; D012996:Solutions; D014333:Tropoelastin