title: Affinity purification of human factor H on polypeptides derived from streptococcal m protein: enrichment of the Y402 variant.
abstract: Recent studies indicate that defective activity of complement factor H (FH) is associated with several human diseases, suggesting that pure FH may be used for therapy. Here, we describe a simple method to isolate human FH, based on the specific interaction between FH and the hypervariable region (HVR) of certain Streptococcus pyogenes M proteins. Special interest was focused on the FH polymorphism Y402H, which is associated with the common eye disease age-related macular degeneration (AMD) and has also been implicated in the binding to M protein. Using a fusion protein containing two copies of the M5-HVR, we found that the Y402 and H402 variants of FH could be efficiently purified by single-step affinity chromatography from human serum containing the corresponding protein. Different M proteins vary in their binding properties, and the M6 and M5 proteins, but not the M18 protein, showed selective binding of the FH Y402 variant. Accordingly, chromatography on a fusion protein derived from the M6-HVR allowed enrichment of the Y402 protein from serum containing both variants. Thus, the exquisite binding specificity of a bacterial protein can be exploited to develop a simple and robust procedure to purify FH and to enrich for the FH variant that protects against AMD.
authors.affiliation: Department of Laboratory Medicine, Lund University, Lund, Sweden ; Department of Veterinary Disease Biology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: O Rickard
authors.initials: OR
authors.lastname: Nilsson
authors.forename: Jonas
authors.initials: J
authors.lastname: Lannergård
authors.forename: B Paul
authors.initials: BP
authors.lastname: Morgan
authors.forename: Gunnar
authors.initials: G
authors.lastname: Lindahl
authors.forename: Mattias C U
authors.initials: MC
authors.lastname: Gustafsson
mesh_terms: D019943:Amino Acid Substitution; D000942:Antigens, Bacterial / Q000737:chemistry* / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D002846:Chromatography, Affinity; D017242:Complement Factor H / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D014644:Genetic Variation; D006801:Humans; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; C493495:CFH protein, human; D002352:Carrier Proteins; D010455:Peptides; C014689:streptococcal M protein; D017242:Complement Factor H