Curli Proteins CsgE and CsgF Inhibit the Aggregation of Human Islet Amyloid Polypeptide

Abstract

Curli, a type of proteinaceous cell surface filament, found on enteric bacteria such as E. Coli and Salmonella, are thought to play an important role in host cell adhesion and invasion. The assembly of CsgA, the major structural protein of Curli, into fibers is aided by three non‐structural proteins, CsgE, CsgF, and CsgG. CsgE and CsgF are thought to be periplasmic chaperone proteins that play a vital role in the assembly of Curli fibers. It has been shown that CsgE is able to prevent the aggregation of CsgA into Curli fibers. We determined the ability of CsgE and CsgF to inhibit the aggregation of human Islet Amyloid Polypeptide (hIAPP), an amyloidogenic protein unrelated to Curli formation. We monitored the aggregation of hIAPP, using the fluorescent dye ThT, in the absence and presence of CsgE and CsgF. An increase in ThT fluorescence emission intensity is routinely used to detect the aggregation of amyloidogenic polypeptides. In the absence of CsgE or CsgF we observe a greater than 5‐fold increase in fluorescence intensity when freshly dissolved hIAPP is monitored in the presence of ThT. Such an increase in intensity is typically taken to indicate the aggregation of hIAPP. In the presence of CsgE and CsgF no significant increase in ThT intensity is observed suggesting that both CsgE and CsgF prevented the aggregation of hIAPP.Support or Funding Information1. This work is supported by NIH grant 1R15GM123430‐01This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.