title: Molecular structure and interaction of recombinant human type XVI collagen.
abstract: Collagen XVI is a minor component of at least two different extracellular fibrillar networks of specialized regions of skin and cartilage. In skin, collagen XVI is integrated into particular fibrillin-rich microfibrils lacking an amorphous elastin core. In cartilage, collagen XVI is a component of small heterotypic D-banded fibrils, mainly occurring in the territorial matrix of chondrocytes. Here, we present the first direct evidence for the molecular structure and functional properties of these fibril-associated collagens with interrupted triple helices (FACIT). We have expressed recombinantly the full-length alpha1 chain of human collagen XVI in HEK 293 EBNA cells in large quantities using an episomal expression system. Secreted full-length recombinant collagen XVI forms stable disulfide-bonded homotrimers and is rapidly proteolytically processed to distinct fragments at specific protease sequence motifs, one resembling an aggrecanase recognition site. Limited trypsin digestion assays and thermal transition curves imply sequential thermal denaturation of individual triple helical domains of this recombinant collagen, similar to authentic collagen XVI. Molecular images of collagen XVI reveal rod-like molecules which harbor multiple sharp kinks attributing a highly flexible structure presumably introduced by non-collagenous (NC) regions. Terminally located cloverleaf-shaped nodules correspond to the large NC NC11 domain of trimeric collagen XVI. The total length of individual trimeric recombinant collagen XVI molecules constitutes about 240 nm as calculated by atomic force and negative staining electron microscopy. Recombinant collagen XVI interacts with fibrillin-1 and with fibronectin indicating multiple molecular interactions in which this ubiquitously expressed and versatile FACIT-collagen can participate. In vitro generated collagen XVI provides an indispensable tool for future determination of its function during supramolecular assembly of matrix aggregates and its role in maintenance, organization and interaction of fibrillar structures.
authors.affiliation: Institut für Physiologische Chemie und Pathobiochemie, Universitätsklinikum Münster, Waldeyerstr. 15, 48149 Münster, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Kassner
authors.forename: Kerstin
authors.initials: K
authors.lastname: Tiedemann
authors.forename: Holger
authors.initials: H
authors.lastname: Notbohm
authors.forename: Thomas
authors.initials: T
authors.lastname: Ludwig
authors.forename: Matthias
authors.initials: M
authors.lastname: Mörgelin
authors.forename: Dieter P
authors.initials: DP
authors.lastname: Reinhardt
authors.forename: Mon-Li
authors.initials: ML
authors.lastname: Chu
authors.forename: Peter
authors.initials: P
authors.lastname: Bruckner
authors.forename: Susanne
authors.initials: S
authors.lastname: Grässel
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D002846:Chromatography, Affinity; D003094:Collagen / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006031:Glycosylation; D006801:Humans; D018625:Microscopy, Atomic Force; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism
chemical_list: C481130:COL16A1 protein, human; D011994:Recombinant Proteins; D003094:Collagen