TY - JOUR T1 - A Structurally Distinct Human Mycoplasma Protein that Generically Blocks Antigen-Antibody Union JF - Science JO - Science SP - 656 LP - 661 DO - 10.1126/science.1246135 VL - 343 IS - 6171 AU - Grover, Rajesh K. AU - Zhu, Xueyong AU - Nieusma, Travis AU - Jones, Teresa AU - Boero, Isabel AU - MacLeod, Amanda S. AU - Mark, Adam AU - Niessen, Sherry AU - Kim, Helen J. AU - Kong, Leopold AU - Assad-Garcia, Nacyra AU - Kwon, Keehwan AU - Chesi, Marta AU - Smider, Vaughn V. AU - Salomon, Daniel R. AU - Jelinek, Diane F. AU - Kyle, Robert A. AU - Pyles, Richard B. AU - Glass, John I. AU - Ward, Andrew B. AU - Wilson, Ian A. AU - Lerner, Richard A. Y1 - 2014/02/07 UR - http://science.sciencemag.org/content/343/6171/656.abstract N2 - Our immune systems can produce a vastly diverse repertoire of antibody molecules that each recognize and bind to a specific foreign antigen via a hypervariable region. However, there are a few bacterial antigens—such as Protein A, Protein G, and Protein L—that instead bind to the antibody's conserved regions and can bind to a large number of different antibodies. These high-affinity broad-spectrum antibody-binding properties have been widely exploited both in the laboratory and in industry for purifying, immobilizing, and detecting antibodies. Grover et al. (p. 656) have now identified Protein M found on the surface of human mycoplasma, which displays even broader antibody-binding specificity. The crystal structure of Protein M revealed how Protein-M binding blocks the antibody's antigen binding site. This mechanism may be exploited by mycoplasma to escape the humoral immune response.We report the discovery of a broadly reactive antibody-binding protein (Protein M) from human mycoplasma. The crystal structure of the ectodomain of transmembrane Protein M differs from other known protein structures, as does its mechanism of antibody binding. Protein M binds with high affinity to all types of human and nonhuman immunoglobulin G, predominantly through attachment to the conserved portions of the variable region of the κ and λ light chains. Protein M blocks antibody-antigen union, likely because of its large C-terminal domain extending over the antibody-combining site, blocking entry to large antigens. Similar to the other immunoglobulin-binding proteins such as Protein A, Protein M as well as its orthologs in other Mycoplasma species could become invaluable reagents in the antibody field. ER -