New protein discovery may have implications for treating deadly E. coli infection

09.11.2005

Queen’s researchers may have opened the door to more effective treatment of a deadly strain of the E. coli bacteria with the discovery of a previously unknown protein.

A team led by biochemistry researcher Zongchao Jia and graduate student Michael Suits has identified a protein that allows the bacterial strain known as E. coli 0157:H7 to obtain the iron it needs for survival in the body.

Iron is a catalyst for bacterial growth, so when a human body detects bacterial invasion, it naturally produces proteins that bind tightly to and restrict iron to limit bacterial growth. In response, bacteria have evolved other methods to acquire iron including detecting and using human heme within proteins such as hemoglobin that transports oxygen from our lungs.

The newly discovered protein breaks down heme, releasing the iron atom stored there for use by the deadly bacteria.

“This discovery opens the door for studying the function of heme iron in this strain of E. coli, and may lead to an understanding of how to therapeutically isolate the protein to keep the bacteria from thriving,” says Dr. Jia.

E. coli 0157:H7 is responsible for the fatal illnesses in the Walkerton tragedy, the illness known as “Hamburger Disease” and the recent evacuation of over a thousand residents from the Kasechewan First Nation reserve. It is most commonly transmitted through undercooked meat, unpasturized milk and infected water sources.

Researchers believe that isolating one of the proteins E. coli 0157:H7 needs for survival will not be enough, however, since the bacteria will migrate to surrounding proteins as iron sources.

Ongoing research is required to examine the functions of several different proteins to find an effective treatment for E. coli 0157:H7, similar to the cocktail used to treat other severe bacterial infections.

The results of the Queen’s study, funded by the Canadian Institutes for Health Research (CIHR) are available at PNAS online today.

Contacts:

Lorinda Peterson, 613.533.3234, lorinda.peterson@queensu.ca or Therese Greenwood, 613.533.6907, therese.greenwood@queensu.ca, Queen’s News and Media Services