We characterized the formation of amyloid fibers by two peptides derived from the CsgA sequence: R5 (133-
151) corresponding to the whole repeating unit R5 and a truncated form of this peptide called R5T (134-143). In the presence
of either of the two peptides: an increase in the fluorescence intensity of Thioflavin T was observed; a shift of the
absorbance of Congo red was measured; spontaneous formation of amyloid fibers was observed by polarized light as well
asatomic force microscopy imaging. Large-size aggregates were observed with R5 while R5T formed fagots of individualized
fibers. The infrared spectroscopy analysis revealed the presence of a greater number of intermolecular bonds for R5.
In conclusion, a 10 aminoacids peptide derived from the R5 sequence was sufficient for the spontaneous formation of
amyloid fibrils but not to form large-size aggregates of fibers.
Keywords: Amyloïd, biofilm, CsgA, Curli, fiber, peptide.
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