title: V gene sequences of lupus-derived human IgM anti-ssDNA antibody: implication for the importance of the location of DNA-binding amino acids.
abstract: Binding and structural characteristics of human IgMk anti-ssDNA antibody 7B3 were determined. 7B3 was derived from Epstein-Barr virus-transformed peripheral blood B cells of a lupus nephritis patient. Purified 7B3 bound ssDNA from various species, but not dsDNA or structurally unrelated antigens. The relative avidity of 7B3 was high in comparison with IgM anti-DNA antibodies previously described by other investigators. Sequence analysis showed that 7B3 used VH26/D35/JH3 and Humkv328h5/JK1 germline genes, and had a few mutations in the complementarity determining regions (CDRs). No arginine was expressed in the heavy-chain CDR3. However, the putative DNA contact sites, based on the previous crystallographic and computer modeling studies, were occupied by mutated or germline-derived basic and polar amino acids. These results suggest that a minimally mutated IgM anti-ssDNA antibody with a paucity of arginines could display monospecificity and high avidity if DNA-binding amino acids are enriched at the critical DNA contact sites.
authors.affiliation: Immunology Research Laboratory, St. Luke's Hospital, Kansas City, Missouri 64111, USA.
authors.forename: R
authors.initials: R
authors.lastname: Suenaga
authors.forename: K
authors.initials: K
authors.lastname: Mitamura
authors.forename: N I
authors.initials: NI
authors.lastname: Abdou
mesh_terms: D000595:Amino Acid Sequence; D000974:Antibodies, Antinuclear / Q000235:genetics*; D000911:Antibodies, Monoclonal / Q000235:genetics*; D000915:Antibody Affinity; D001120:Arginine / Q000378:metabolism*; D001327:Autoimmune Diseases / Q000235:genetics* / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D001483:Base Sequence; D002461:Cell Line, Transformed; D004277:DNA, Single-Stranded / Q000276:immunology* / Q000378:metabolism; D015322:Gene Rearrangement, B-Lymphocyte; D005803:Genes, Immunoglobulin; D004854:Herpesvirus 4, Human; D006801:Humans; D007144:Immunoglobulin J-Chains / Q000235:genetics; D007075:Immunoglobulin M / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D007145:Immunoglobulin kappa-Chains / Q000235:genetics; D008180:Lupus Erythematosus, Systemic / Q000235:genetics* / Q000276:immunology; D008181:Lupus Nephritis / Q000235:genetics / Q000276:immunology / Q000473:pathology; D008239:Lysine / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment; D017385:Sequence Homology
chemical_list: D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D004277:DNA, Single-Stranded; D007144:Immunoglobulin J-Chains; D007075:Immunoglobulin M; D007135:Immunoglobulin Variable Region; D007145:Immunoglobulin kappa-Chains; D001120:Arginine; D008239:Lysine