January 2012

How H. pylori deals with stomach acid


The Journal of Biological Chemistry has such a rich history that the editors and staff members thought it was only fitting that the final print edition’s cover convey the vibrant colors of past editions. They wrote, in part: “We ... recognize that inspiration often emerges in unexpected ways— thanks to a patchwork of
people and ideas. Next week, the JBC will begin a new phase of its existence ... enabling us to roll out new forms of scientific communication that were not possible with conventional print. But, rest assured, showcasing images that tell scientific stories remains a priority, and we’re looking forward to presenting our authors’ finest artwork in innovative ways on the Web.”

Helicobacter pylori can cause stomach ulcers and cancer. The pathogenic bacterium survives in the acidic conditions of the human stomach by hydrolyzing urea into ammonia to neutralize the stomach acid. Urease is the critical enzyme that undertakes the hydrolysis, but it only becomes active with the help of the accessory proteins, which include UreF, UreH and UreG. “Although UreF, UreG and UreH are well-known players involved in urease maturation, their biochemical roles have remained enigmatic over the years,” explains Kam-Bo Wong at the Chinese University of Hong Kong. In a recent Paper of the Week in the Journal of Biological Chemistry, Wong and colleagues established the crystal structure of the complex formed by UreF and UreH. They found that UreH induced conformational changes in UreF, which in turn recruited the third accessory protein, UreG, to form the essential complex for urease activation. During their study, the investigators had to solve a puzzle: “Our biochemical experiments initially showed that the highly conserved C-terminal tail of UreF was essential for interaction with UreH. But when we solved the structure of UreF, we found that this highly conserved region of UreF was missing,” says Wong. “It wasn’t until we solved the UreF-UreH complex structure that we discovered that the conserved C-terminal residues of UreF become structured only when in complex with UreH.” Wong says the work has clinical potential. With the complex’s crystal structure in hand, researchers can now search for small molecules that disrupt the assembly of the complex and halt urease maturation.

Rajendrani Mukhopadhyay (rmukhopadhyay@asbmb.org) is the senior science writer for ASBMB Today and the technical editor for the JBC.

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