The bacterium Escherichia coli, commonly known E. coli, has a duplicitous reputation.

Scientists tell us that most strains of the microbe live peacefully in our guts or the guts of other mammals, munching on bits of food, causing no harm or even creating benefits for their hosts.

But the grotesque imagery of E. coli infections tells a different story: After eating food contaminated with pathogenic strains, people can experience vomiting, diarrhea, and dysentery. And in rare case, the bacteria can lead to kidney failure and even death.

Ken Campellone, assistant professor of molecular and cell biology in the College of Liberal Arts and Science, wants to understand how these bacteria can play such different roles. By focusing on the interactions between one of the deadliest E. coli strains and the cells of the human gut, he’s learning not only how the bacteria work, but how our own cells work, too.

Recently, Campellone discovered a particular protein in the cells of the human large intestine that is taken over by E. Coli cells and helps to bind the bacterium to the intestinal wall.

“Pathogens have found really clever ways of taking over the normal processes of our cells,” he says. “Often they know more about our own cells than we do, and it’s really intriguing.”

The strain of E. coli that Campellone studies belongs to a group of the bacteria called Enterohemorrhagic E. coli, or EHEC, that often makes international news when people eat contaminated meat or vegetables. In 2011, an outbreak of a hemorrhagic strain in Germany infected more than 3,7000 pee, killing 45. The centers for Disease Control and Prevention estimate that about 75,000 infections occur each year in the United States.

The reason for this high level of virulence, say Campellone, is a series of genetic acquisition by the harmful bacteria. Scientists have sequenced several types of E. coli, and they’ve found more than 1,000 genes in the harmful group that are not present in the harmless, or commensal, group. But, he adds, of the roughly 1,000 genes that have been identified as pathogenic, relatively few have been characterized.

“We know very little about the genes in EHEC that are different from the commensal (commensalism: in ecology, is a class of relationships between two organisms benefit From each other) version,” he says, “My goal to better understand how a group of genes that encode proteins called effectors take over their human cell targets.”

What is the symbiotic relationship between E. coli and humans?

The human body provide E. coli with a comfortable living environment in which thebacteria receive the required nutrients for reproduction and growth. E. coli, in turn,makes it possible for humans to absorb vital nutrients, including Vitamin K through colon.

In particular, the most dangerous types have acquired the genes to produce a poisonous substance called Shiga toxin, which Campellone says can produce an illness ranging from unpleasant to life-threatening.

“If the toxin is just released into your intestines, you would get diarrhea and dysentery,” he says. “But if it enters your bloodstream, it can cause serious kidney damage and become fatal.” Plus, he adds, there are currently no known medicines for the blood poisoning syndrome and antibiotics only make only make the symptoms worse. Patients just have to wait and hope.

Campellone’s research focuses on how the trafficking and organization of proteins control the shape of cells. When E. coli affix themselves to the intestinal wall, they disrupt its normal organization. They do this by delivering bacterial proteins into the cell, which in turn recruit specific intestinal cell proteins that normally shape the cell.