E. coli bacteria expressing the functional amyloid fiber, curli.
Colony image showing curli-expressing cells in yellow.
Purified CsgA protein forms amyloid fibers in vitro that are biochemically and structurally similar to curli fibers produced in vivo.
2-Pryidones and Amyloid Formation-- Fredrik Almqvist in Umeå Sweden has developed a library of peptidomimetic compounds that can be potent amyloid modifiers. We are using these 2-pyridone molecules as tools to better understand amyloid formation, and also as inhibitors of amyloid-dependent bacterial processes such as biofilm formation.
High-resolution EM analysis of purified CsgG-his protein reveals donut-shaped structures approximately 15 nM in diameter.
Negative-stain electron microscopy shows that curli are 4-7-nm wide fibers of varying lengths.
Bacterial amyloid fibers formed by the polymerization of the CsgA protein from E. coli.
Freeze-fracture, deep-etch electron micrograph showing colonies of curliated E. coli after 48 hours of growth. Curli fibers surround and connect individual bacteria into small groups.
Curli are extracellular organelles produced by Escherichia coli and certain Salmonella species. These fibers are structurally and biochemically identical to eukaryotic amyloid fibers, which underlie diverse mammalian ailments including Alzheimer’s disease (AD), systemic amyloidosis, bovine spongiform encephalopathy (mad cow disease), and Creutzfeldt-Jacob disease, among others.
The Chapman lab uses the curli system to study the fundamental principles of amyloid formation. We continue to dissect the biogenesis of curli fibers, as well as the consequences of curli amyloid formation on the biology of microbial communities.