[2] These fibers serve to promote cell community behavior through biofilm formation in the extracellular matrix.

[2][3] The study of curli may help to understand human diseases thought to arise from improper amyloid fiber formation.

The csgBA operon encodes the major structural subunit of curli, CsgA, as well as the nucleator protein, CsgB.

It has long been believed that bacterial growth at a temperature below 30 °C promotes curli gene expression.

[8] Additionally, when there is a lack of salt and nutrients such as nitrogen, phosphate or iron, curli gene expression is stimulated.

[7][9] The curli protein is considered a PAMP (Pathogen-associated molecular pattern); its β-sheet structure is recognized in the innate immune system and activates the TLR2 (Toll-Like Receptor 2).

Since these biofilms allow for the bacteria to survive chemical and physical stressors within their environment, not only do they make patients more susceptible to infection when using shared appliances, but curli and other biofilms have been shown to reduce the infected individuals' immune response and antimicrobials.

[9] CsgB, also known as the minor subunit, is required for the nucleation and organization of CsgA into a curli fiber on cell surfaces.

[6][9] The CsgC subunit was only recently discovered to prevent the aggregation and polymerization of the CsgA protein.