This family consists of several bacterial repeats of around 30 residues in length. These repeats are often found in multiple copies in the curlin proteins CsgA and CsgB. Curli fibres are thin aggregative surface fibres, connected with adhesion, which bind laminin, fibronectin, plasminogen, human contact phase proteins, and major histocompatibility complex (MHC) class I molecules. Curli fibres are coded for by the csg gene cluster, which is comprised of two divergently transcribed operons. One operon encodes the csgB, csgA, and csgC genes, while the other encodes csgD, csgE, csgF, and csgG. The assembly of the fibres is unique and involves extracellular self-assembly of the curlin subunit (CsgA), dependent on a specific nucleator protein (CsgB). CsgD is a transcriptional activator essential for expression of the two curli fibre operons, and CsgG is an outer membrane lipoprotein involved in extracellular stabilisation of CsgA and CsgB [1].

1: Curli fibers mediate internalization of Escherichia coli by eukaryotic cells. Gophna U, Barlev M, Seijffers R, Oelschlager TA, Hacker J, Ron EZ; Infect Immun 2001;69:2659-2665. PMID:11254632