title: Identification of the first prokaryotic collagen sequence motif that mediates binding to human collagen receptors, integrins alpha2beta1 and alpha11beta1.
abstract: Many pathogenic bacteria interact with human integrins to enter host cells and to augment host colonization. Group A Streptococcus (GAS) employs molecular mimicry by direct interactions between the cell surface streptococcal collagen-like protein-1 (Scl1) and the human collagen receptor, integrin alpha2beta1. The collagen-like (CL) region of the Scl1 protein mediates integrin-binding, although, the integrin binding motif was not defined. Here, we used molecular cloning and site-directed mutagenesis to identify the GLPGER sequence as the alpha2beta1 and the alpha11beta1 binding motif. Electron microscopy experiments mapped binding sites of the recombinant alpha2-integrin-inserted domain to the GLPGER motif of the recombinant Scl (rScl) protein. rScl proteins and a synthetic peptide harboring the GLPGER motif mediated the attachment of C2C12-alpha2+myoblasts expressing the alpha2beta1 integrin as the sole collagen receptor. The C2C12-alpha11+myoblasts expressing the alpha11beta1 integrin also attached to GLPGER-harboring rScl proteins. Furthermore, the C2C12-alpha11+cells attached to rScl1 more efficiently than C2C12-alpha2+cells, suggesting that the alpha11beta1 integrin may have a higher binding affinity for the GLPGER sequence. Human endothelial cells and dermal fibroblasts adhered to rScl proteins, indicating that multiple cell types may recognize and bind the Scl proteins via their collagen receptors. This work is a stepping stone toward defining the utilization of collagen receptors by microbial collagen-like proteins that are expressed by pathogenic bacteria.
authors.affiliation: Department of Microbiology, Immunology, and Cell Biology and Mary Babb Randolph Cancer Center, West Virginia University School of Medicine, Morgantown, West Virginia 26506, USA.
authors.forename: Clayton C
authors.initials: CC
authors.lastname: Caswell
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Barczyk
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Keene
authors.forename: Ewa
authors.initials: E
authors.lastname: Lukomska
authors.forename: Donald E
authors.initials: DE
authors.lastname: Gullberg
authors.forename: Slawomir
authors.initials: S
authors.lastname: Lukomski
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism; D003094:Collagen / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D038982:Integrin alpha2beta1 / Q000378:metabolism*; D016023:Integrins / Q000378:metabolism*; D051379:Mice; D016297:Mutagenesis, Site-Directed; D038981:Receptors, Collagen / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D038982:Integrin alpha2beta1; D016023:Integrins; D038981:Receptors, Collagen; D011994:Recombinant Proteins; C423454:Scl1 protein, Streptococcus; C467800:integrin alpha11beta1; D003094:Collagen