The type 2 secretion and type 4 pilus systems of Escherichia coli - Escherichia coli: Pathotypes and Principles of Pathogenesis - page 381

TABLE 13.1 Common and unique proteins of E. coli T2S and T4P
systems—cont'd

System

Type 2
secretion

Protein description BFP Longus CFA/III R64 HCP

Outer membrane
protein, forms
complex with secretin

- BfpG LngC CofC -

Soluble protein
essential for pilus
biogenesis

- BfpU LngG CofG -

Putative lytic
transglycosylase

- BfpH LngT CofT PilT b2854

Lipoprotein - - - - PilL

Bitopic inner-
membrane protein

- BfpL - -

Protein of unknown
function

- - LngF CofF -

Protein of unknown
function

- - LngJ CofJ -

Inner membrane
protein of unknown
function

- - - - PilK

Inner membrane
protein of unknown
function

- - - - PilM

Inner membrane
protein of unknown
function

- - - - PilP

Outer membrane
protein of unknown
function

- - - - PilO

A polytopic IM protein, GspF, is not only well-conserved in the T4P and T2S
machines, but also has homologs in the archaeal flagella system and Gram-
positive competence systems ( Peabody et al., 2003 ). A bitopic transmembrane
protein, GspL, interacts in the IM with GspM, another bitopic protein that is
predominantly periplasmic ( Sandkvist et al., 1999, 2000 ; Abendroth et al.,
2004a, 2009a ). The cytoplasmic domain of GspL interacts with the hexameric