Abstract

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.