Article

Curli Biogenesis and Function

Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA.
Annual Review of Microbiology (Impact Factor: 12.18). 02/2006; 60(1):131-47. DOI: 10.1146/annurev.micro.60.080805.142106
Source: PubMed

ABSTRACT

Curli are the major proteinaceous component of a complex extracellular matrix produced by many Enterobacteriaceae. Curli were first discovered in the late 1980s on Escherichia coli strains that caused bovine mastitis, and have since been implicated in many physiological and pathogenic processes of E. coli and Salmonella spp. Curli fibers are involved in adhesion to surfaces, cell aggregation, and biofilm formation. Curli also mediate host cell adhesion and invasion, and they are potent inducers of the host inflammatory response. The structure and biogenesis of curli are unique among bacterial fibers that have been described to date. Structurally and biochemically, curli belong to a growing class of fibers known as amyloids. Amyloid fiber formation is responsible for several human diseases including Alzheimer's, Huntington's, and prion diseases, although the process of in vivo amyloid formation is not well understood. Curli provide a unique system to study macromolecular assembly in bacteria and in vivo amyloid fiber formation. Here, we review curli biogenesis, regulation, role in biofilm formation, and role in pathogenesis.

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    • "Curli were first discovered in the 247 late 1980s on E. coli strains that caused bovine mastitis and these are mainly involved in 248 adhesion to surfaces, cell aggregation, and biofilm formation (Austin et al., 2008). Curli also 249 mediate host cell adhesion and invasion, and they are potent inducers of the host inflammatory 250 response (Barnhart and Chapman, 2006). Isolates of Salmonella spp. "
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    • "A major protein component is curli (amyloid fimbriae), encoded by csg operons (Yaron and Römling 2014). Protein BapA constitutes another important component of the matrix (Barnhart and Chapman 2006) and major biofilm exopolysaccharides are cellulose (Zogaj et al. 2001) and colonic acid (Gibson et al. 2006). Adhesionmediated type I fimbriae, Lpf and Pef, also contribute to the early steps of biofilm formation (Ledeboer et al. 2006). "
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    • "Transcriptional regulator and periplasmic proteins csgD and csgF , involved in curli biosynthesis , were also detected on 1 day in UC1CITii ( Barnhart and Chapman , 2006 ) . It is unclear whether curli expression in UC1CITii is promoting adherence to one another or host adherence , as it is capable of both ( Barnhart and Chapman , 2006 ) . Citrobacter ' s affinity for host fucosylated glycans would suggest colonization of the mucosa . "
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