The Curli Accessory Protein CsgF of Salmonella Typhimurium Influences the in vitro Aggregation of Human Islet Amyloid Polypeptide

The Curli secretion gene product F (CsgF) is a critical component of the assembly of Curli, proteinaceous filaments, found on the outer surface of gram-negative bacteria such as <i>E. Coli</i> and <i>Salmonella</i> . Herein we describe the ability of CsgF to influence the in-vitro aggregation of human islet amyloid polypeptide (hIAPP), an amyloidogenic polypeptide that is unrelated to Curli. In the presence of CsgF no increase in Thioflavin T fluorescence was observed for freshly solubilized hIAPP monitored as a function of time, suggesting that CsgF prevents the aggregation of hIAPP during the period of observation. A variant of CsgF lacking the first 65 residues in the N-terminus of CsgF retained the ability to inhibit the aggregation of hIAPP suggesting that the ability of CsgF to inhibit the aggregation of hIAPP is mediated by the C-terminal half of the protein.