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Bacteria produce fibers similar to those in Alzheimer's disease
  
By
Edward R. Winstead


 

Common bacteria produce proteins that are remarkably similar to those found in the brains of Alzheimer's patients, according to a new study. Scientists found that E. coli bacteria generate protein fibers with the characteristics of amyloids—the proteins that accumulate in the brain during debilitating human ailments such as Alzheimer's and prion diseases.


EM micrograph of curliated E. coli. View larger

Bacteria use extracellular fibers, called curli, to colonize surfaces and mediate interactions with proteins in host cells. The discovery of bacterial amyloids gives researchers a new tool for investigating the details of how amyloids form in humans and for developing drugs to block their formation.

The discovery "also raises the intriguing possibility that bacterial amyloids could play a role in certain human neurodegenerative and amyloid-related diseases," the researchers write in Science. Scott J. Hultgren, of Washington University School of Medicine, St. Louis, Missouri, led the study.

The researchers used biochemical, biophysical, and imaging analyses to determine that the curli fibers produced by E. coli were in fact amyloid. They found differences as well as similarities between bacterial fibers and those associated with human disease. Amyloids in humans, for example, seem to assemble spontaneously, while bacteria have a specific machinery designed to assemble curli fibers.

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Chapman, M.R. et al. Role of Escherichia coli curli operons in directing amyloid fiber formation. Science 295, 851-855 (February 1, 2002).
 

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