title: [In vitro evolutional selection of a combinatorial phage library displaying randomly-rearranged various binding domains of SpA and SpG with four human IgG subclasses].
abstract: Protein A and protein G are two well-defined immunoglobulin (Ig)-binding proteins (IBPs), which show affinity for specific sites on Ig of mammalian hosts. Protein A and protein G contained several highly homologous IgG-binding domains which had been demonstrated to have function to bind to IgG. Whether combinations of Ig-binding domains of various IBPs could produce useful novel binding properties remains interesting. We constructed a combinatorial phage library which displayed randomly-rearranged A, B, C, D and E domains of protein A, B2 and B3 domains of protein G. Four rounds molecular evolution of this library directed by all four human IgG subclasses respectively generated a common arrangement of D-C respectively which didn't exist in SpA. The dynamic loss of control phages and increase of the phages displaying two or more binding domains, especially the selective enrichment of D-C and strict selection of its linking peptides demonstrated the efficient molecular evolutions and the significance of the selected D-C arrangement. The phage binding assays confirmed that D-C possessed a binding advantage with four human IgG subclasses compared to SpA. In this work, a novel combination of Ig-binding domains, D-C, was obtained and presented the novel Ig binding properties which provided a novel candidate molecule for the purification, production and detection of IgG antibodies and a new approach for the further study of structures and functions of IBPs.
authors.affiliation: Department of Microbiology, Second Military Medical University, Shanghai 200433, China.
authors.forename: Peipei
authors.initials: P
authors.lastname: Qi
authors.forename: Yingying
authors.initials: Y
authors.lastname: Ding
authors.forename: Lili
authors.initials: L
authors.lastname: Wu
authors.forename: Qiuli
authors.initials: Q
authors.lastname: Chen
authors.forename: Jinhong
authors.initials: J
authors.lastname: Wang
authors.forename: Chao
authors.initials: C
authors.lastname: Liu
authors.forename: Wenting
authors.initials: W
authors.lastname: Liao
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Cao
authors.forename: Wei
authors.initials: W
authors.lastname: Pan
mesh_terms: D000595:Amino Acid Sequence; D000918:Antibody Specificity; D001426:Bacterial Proteins / Q000276:immunology / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive; D019143:Evolution, Molecular; D007074:Immunoglobulin G / Q000276:immunology / Q000378:metabolism*; D008969:Molecular Sequence Data; D019151:Peptide Library; D016415:Sequence Alignment; D013205:Staphylococcal Protein A / Q000276:immunology / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C034284:IgG Fc-binding protein, Streptococcus; D007074:Immunoglobulin G; D019151:Peptide Library; D013205:Staphylococcal Protein A