A protein that allows some bacteria to cling to and invade host cells could be a target for combating infection.

Credit: HYEILIN HAM

Kim Orth and her colleagues at the University of Texas Southwestern Medical Center in Dallas searched for such proteins in the bacterium Vibrio parahaemolyticus, which can cause food poisoning. They found MAM7, a protein that is expressed in the bacterial outer membrane. Deleting the MAM7 gene decreased the bacterium's ability to bind to and kill human and mouse cells. Nematode worms fed the pathogenic bacterium died (pictured bottom) faster than did those exposed to harmless Escherichia coli (top).

Exposure of human cells to benign E. coli engineered to express MAM7 rendered the cells more resistant to infection by V. parahaemolyticus and other pathogenic bacteria. This suggests that the E. coli's MAM7 blocked key binding sites needed by the bacterial invaders, providing a new way to fight infection.

Proc. Natl Acad. Sci. USA doi:10.1073/pnas.1102360108 (2011)