Survivor Bacteria
Helicobacter pylori , the gut bacterium that causes ulcer and cancer, has troubled scientists for a while. The bug manages to survive in the acidic environment of our stomach. Scientists assumed that urease, an enzyme found on its surface, broke down urea to produce ammonia, which neutralised the acid. George Sachs and his colleagues at the University of California at Los Angeles, USA, have found that it is not the urease on the surface but that inside the cell which neutralises the acid. UreI, a protein on the cell's inner membrane, acts as a gatekeeper, allowing only a small quantity of stomach acid into the cell at a time to avoid being overwhelmed. Sachs hopes drugs can be developed that switch off UreI, destroying the bacterium and thus avoiding cancer and ulcers ( New Scientist , Vol 165, No 2223).