title: A novel binding site in collagen type III for integrins alpha1beta1 and alpha2beta1.
abstract: Previously identified high affinity integrin-binding motifs in collagens, GFOGER and GLOGER, are not present in type III collagen. Here, we first characterized the binding of recombinant I domains from integrins alpha(1) and alpha(2) (alpha(1)I and alpha(2)I) to fibrillar collagen types I-III and showed that each I domain bound to the three types of collagens with similar affinities. Using rotary shadowing followed by electron microscopy, we identified a high affinity binding region in human type III collagen recognized by alpha(1)I and alpha(2)I. Examination of the region revealed the presence of two sequences that contain the critical GER motif, GROGER and GAOGER. Collagen-like peptides containing these two motifs were synthesized, and their triple helical nature was confirmed by circular dichroism spectroscopy. Experiments show that the GROGER-containing peptide was able to bind both alpha(1)I and alpha(2)I with high affinity and effectively inhibit the binding of alpha(1)I and alpha(2)I to type III and I collagens, whereas the GAOGER-containing peptide was considerably less effective. Furthermore, the GROGER-containing peptide supported adhesion of human lung fibroblast cells when coated on a culture dish. Thus, we have identified a novel high affinity binding sequence for the collagen-binding integrin I domains.
authors.affiliation: The Center for Extracellular Matrix Biology, Texas A&M University Health Science Center, Institute of Bioscience and Technology, Houston, 77030, USA.
authors.forename: Jiyeun Kate
authors.initials: JK
authors.lastname: Kim
authors.forename: Yi
authors.initials: Y
authors.lastname: Xu
authors.forename: Xuejun
authors.initials: X
authors.lastname: Xu
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Keene
authors.forename: Sivashankarappa
authors.initials: S
authors.lastname: Gurusiddappa
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Liang
authors.forename: Kishore K
authors.initials: KK
authors.lastname: Wary
authors.forename: Magnus
authors.initials: M
authors.lastname: Höök
mesh_terms: D020816:Amino Acid Motifs; D001483:Base Sequence; D001665:Binding Sites; D002448:Cell Adhesion; D002942:Circular Dichroism; D003094:Collagen / Q000737:chemistry; D024061:Collagen Type III / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D039222:Integrin alpha1beta1 / Q000378:metabolism*; D038982:Integrin alpha2beta1 / Q000737:chemistry*; D016023:Integrins / Q000378:metabolism; D007700:Kinetics; D008168:Lung / Q000378:metabolism; D008854:Microscopy, Electron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D012984:Software; D020349:Surface Plasmon Resonance; D013997:Time Factors
chemical_list: D024061:Collagen Type III; D039222:Integrin alpha1beta1; D038982:Integrin alpha2beta1; D016023:Integrins; D010455:Peptides; D011994:Recombinant Proteins; D003094:Collagen