Identification of Amino Acid Conservation in The Curli Accessory Protein CsgF.

The Curli-Specific gene product F (CsgF) plays an important role in the assembly of gram-negative bacterial cell surface filaments known as Curli. In order to evaluate amino acid conservation in the context of the solution and CsgG bound structures of CsgF we carried out a multiple sequence alignment of CsgF sequences from 35 gram-negative bacteria and correlated amino acid conservation to structural and functional importance. We identified conserved Pro and Gly residues within the N-terminal region of CsgF that may be required to adopt the loop confirmation observed in this region. Several conserved hydrophobic residues are found on the 3rd and 4th β-strands of the C-terminal β-sheet and extending to the C-terminal end, that may play a role in the reported observation that the C-terminus is needed for Curli formation. The importance of several conserved residues that were identified in this study has not yet been reported and investigating their impact on the structure and function of CsgF may add to our understanding of Curli assembly.