Type IV filament

The type IV filament superfamily (TFF) is a group of fibrous protein structures that includes a set of cell projections with evolutionarily related membrane proteins.^[1] The TFF family seems to have originated in the last universal common ancestor, from where it diversified into archaella, type IV pili, type II secretion systems, and the Tad pili.^[2]

Complexes in the TFF superfamily are unified by the presence of the eponymous type IV pilin, an AAA+ ATPase, an integral (cytoplasmic) membrane (IM) platform, and (with the exception of MSH) a prepilin peptidase.^[2]