Antibody-Loving Protein Binds Around

A wildly promiscuous protein produced by pathogenic Mycoplasma, such as those that cause genital and respiratory tract infections, appears to have the ability to bind any antibody it encounters—including those from humans, mice, rabbits, pigs, and goats. In doing so, the protein covers up the variable section of the antibodies, preventing them from hooking up with their intended targets (Science 2014, DOI: 10.1126/science.1246135). Researchers led by Richard A. Lerner of Scripps Research Institute California have named the antibody-interfering molecule Protein M. They believe it is unique because its crystal structure does not appear in the Protein Data Bank, the international online structure repository. Protein M is not the only pathogenic protein known to bind a variety of antibodies, but it is the largest discovered to date. Lerner’s team proposes that the protein could find good use in industry as a tool to purify antibodies. Still to be learned is exactly how the bacteria employ the protein for their own gain, although the pathogens presumably produce the protein to interfere with host immune responses and thus allow chronic infection.