TABLE 3.

Conserved proteins in type IV pilus biogenesis and related systems

Homologuea							Characteristic
R64	EPEC	V. cholerae	P. aeruginosa	N. gonorrhoeae	GSP	Bsu
PilS	BfpA	TcpA	PilA	PilE			Prepilin
PilU	BfpP	TcpJ	PilD	PilD	PulO	ComC	Prepilin peptidase
PilN	BfpB	TcpC	PilQ	PilQ	PulD		Outer membrane protein
PilQ	BfpD	TcpT	PilB	PilF	PulE	ComGA	Nucleotide binding protein
PilR	BfpE	TcpE	PilC	PilG	PulF	ComGB	Integral membrane protein
PilT	BfpH						Gene X homologue
PilV	BfpI, -J, and -K		PilE, -V, -W, and -X; FimT and -U		PulG, -H, -I, and -J	ComGC, -GD, and -GE	Prepilin peptidase cleavage site

^aEPEC, enteropathogenic E. coli; GSP, pullulanase secretion system of Klebsiella oxytoca; Bsu, competence system of Bacillus subtilis. Results are summarized from references 1, 2, 8, 9, 14, 22–24, and 27–30.