TraF is a 26 kDa periplasmic protein necessary for F pilus extension, and deletions at either termini abolish F pili formation eliminating conjugative gene transfer. The NTD of TraF exhibits increased structural dynamics and is responsible for interactions with TraH; the CTD (Glu127-Leu247) contains a thioredoxin-like fold. Through Phyre2 modeling the structure of TraF is predicted to have at least three -helices bordered by a four-strand -sheet.