Lipid Cues Meningitis Bacteria’s Lethality

A bacterium behind meningitis and the blood infection septicemia resides in up to 30% of human throats, but it’s only when the germ cuts ties with throat colonies and moves to the brain or blood that it can become deadly. Scientists in France have now identified a chemical switch that makes this microbe go rogue (Science, DOI: 10.1126/science.1200729). Neisseria meningitidis attaches to throat tissue through hairlike protein appendages called pili, and the chemical modifications on pili intrigued Guillaume Duménil of the French National Institute of Health & Medical Research and his coworkers. Using mass spectrometry, Duménil’s team noticed that when the bacteria grow in contact with host cells they produce more of an enzyme that coats pili with the lipid phosphoglycerol. The researchers’ biochemical experiments and computer models suggest phosphoglycerol disrupts contacts between pili surfaces because of its negative charge and its bulk. They propose that phosphoglycerol modification lets some microbes stay in throat colonies and lets others detach to make trouble elsewhere.