Study: E. Coli Produces Amyloid Fibers Similar to Those Found in Alzheimer Patients

Certain strains of the bacterium Escherichia coli (E. Coli) produce amyloid fibers similar to those found in the brains of patients with Alzheimer's disease, according to researchers at Washington University School of Medicine.

The bacterial fibers, known as curli, form a meshwork around the bacteria, producing clusters known as biofilms. Bacteria in biofilms are more resistant to antibiotics and the body's immune system. This is the first time that amyloid has been seen in bacteria.

Amyloid was previously thought to be made by cells of higher organisms and their presence was considered to be a biological error, according to the researchers.

"This is the first example of a dedicated molecular machinery to produce amyloid and thus shows that amyloid production is not always a mistake," said Scott J. Hultgren, PhD, lead author of the study. "This finding gives us a powerful genetic system to study the molecular details of amyloid formation and may allow us to begin designing drugs that will block the formation of amyloid or treat or prevent human amyloid disease."

Researchers speculate that bacterial infection may play a role in amyloid diseases such as Alzheimer's disease. In amyloid diseases, dissolved amyloid proteins change their shape and aggregate into fibers. When those fibers develop in the brain, it causes Alzheimer's disease.

"The question is, what causes the soluble protein in human disease to convert into amyloid fibers? We can now study that mechanism in E. coli," said Hultgren.

"Learning that bacteria produce amyloid is a revelation," said Paul Berg, Cahill Professor of Cancer Research and Biochemistry, Emeritus, at Stanford University School of Medicine.

"That discovery provides an additional vantage point from which to assess the role of amyloid production and accumulation in Alzheimer's disease and related neuro-pathologies. Hopefully, this model will reveal clues for preventing the devastating formation of amyloid plaques characteristic of those diseases," Berg said.

Other sources: Washington University School of Medicine