SURVIVING IN AN ACID BATH

Abstract

THE ULCER-CAUSING BACTEria called Helicobacter pylori fascinate researchers. These bacteria live in human stomachs, which once were thought uninhabitable because of the extremely acidic conditions they harbor. H. pylori 's survival in the gut is known to be due to its high production of urease. When this enzyme hydrolyzes urea, the ammonia formed neutralizes the acidity around the bacterium, creating a livable microenvironment. Now, the crystal structure of H. pylori urease is providing more clues to the bacteria's survival tactics. The structure was obtained recently by Byung-Ha Oh and coworkers at Pohang University of Science & Technology and at Catholic University of Daegu, both in South Korea [ Nat. Struct. Biol. , 8,505(2001)]. Unlike other ureases, H.pylori urease molecules reside both inside the cytoplasm and on the cell surface. The surface molecules come from spontaneous lysis of other H.pylori , which releases ureases that then adsorb onto the surface of intact bacteria. Scientists have believed ...