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1. Cell surface-localized CsgF condensate is a gatekeeper in bacterial curli subunit secretion

   https://doi.org/10.1038/s41467-023-38089-1  

   Swasthi, Hema M. ; Basalla, Joseph L. ; Dudley, Claire E. ; Vecchiarelli, Anthony G. ; Chapman, Matthew R. ( April 2023 , Nature Communications)

   Curli are functional amyloids present on the outer membrane ofE. coli. CsgF is required for the proper assembly of curli. Here, we found that the CsgF phase separates in vitro and that the ability of CsgF variants to phase-separate is tightly correlated with CsgF function during curli biogenesis. Substitution of phenylalanine residues in the CsgF N-terminus both reduced the propensity of CsgF to phase-separate and impaired curli assembly. Exogenous addition of purified CsgF complementedcsgF ⁻cells. This exogenous addition assay was used to assess the ability of CsgF variants to complementcsgF ^‒cells. CsgF on the cell surface modulated the secretion of CsgA, the curli major subunit, to the cell surface. We also found that the CsgB nucleator protein can form SDS-insoluble aggregates within the dynamic CsgF condensate. We propose that these multicomponent CsgF-B condensates form a nucleation-competent complex that templates CsgA amyloid formation on the cell surface.

    

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2. Assembly of ordered DNA-curli fibril complexes during Salmonella biofilm formation correlates with strengths of the type I interferon and autoimmune responses

   https://doi.org/10.1371/journal.ppat.1010742  

   Nicastro, Lauren K. ; de Anda, Jaime ; Jain, Neha ; Grando, Kaitlyn C. ; Miller, Amanda L. ; Bessho, Shingo ; Gallucci, Stefania ; Wong, Gerard C. ; Tükel, Çagla ( August 2022 , PLOS Pathogens)

   Baumler, Andreas J. (Ed.)

   Deposition of human amyloids is associated with complex human diseases such as Alzheimer’s and Parkinson’s. Amyloid proteins are also produced by bacteria. The bacterial amyloid curli, found in the extracellular matrix of both commensal and pathogenic enteric bacterial biofilms, forms complexes with extracellular DNA, and recognition of these complexes by the host immune system may initiate an autoimmune response. Here, we isolated early intermediate, intermediate, and mature curli fibrils that form throughout the biofilm development and investigated the structural and pathogenic properties of each. Early intermediate aggregates were smaller than intermediate and mature curli fibrils, and circular dichroism, tryptophan, and thioflavin T analyses confirmed the establishment of a beta-sheet secondary structure as the curli conformations matured. Intermediate and mature curli fibrils were more immune stimulatory than early intermediate fibrils in vitro . The intermediate curli was cytotoxic to macrophages independent of Toll-like receptor 2. Mature curli fibrils had the highest DNA content and induced the highest levels of Isg15 expression and TNFα production in macrophages. In mice, mature curli fibrils induced the highest levels of anti-double-stranded DNA autoantibodies. The levels of autoantibodies were higher in autoimmune-prone NZBWxF/1 mice than wild-type C57BL/6 mice. Chronic exposure to all curli forms led to significant histopathological changes and synovial proliferation in the joints of autoimmune-prone mice; mature curli was the most detrimental. In conclusion, curli fibrils, generated during biofilm formation, cause pathogenic autoimmune responses that are stronger when curli complexes contain higher levels of DNA and in mice predisposed to autoimmunity. 

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3. Influence of the amyloid dye Congo red on curli, cellulose, and the extracellular matrix in E. coli during growth and matrix purification

   https://doi.org/10.1007/s00216-016-9868-2  

   Reichhardt, Courtney ; McCrate, Oscar A. ; Zhou, Xiaoxue ; Lee, Jessica ; Thongsomboon, Wiriya ; Cegelski, Lynette ( November 2016 , Analytical and Bioanalytical Chemistry)
4. Enzymatic Degradation of Polyethylene Terephthalate Plastics by Bacterial Curli Display PETase

   https://doi.org/10.1021/acs.estlett.2c00332  

   Zhu, Baotong ; Ye, Quanhui ; Seo, Yoonjoo ; Wei, Na ( July 2022 , Environmental Science & Technology Letters)
5. Phosphoethanolamine cellulose enhances curli-mediated adhesion of uropathogenic Escherichia coli to bladder epithelial cells

   https://doi.org/10.1073/pnas.1801564115  

   Hollenbeck, Emily C. ; Antonoplis, Alexandra ; Chai, Chew ; Thongsomboon, Wiriya ; Fuller, Gerald G. ; Cegelski, Lynette ( September 2018 , Proceedings of the National Academy of Sciences)