Import of colicins across the outer membrane of Escherichia coli involves multiple protein interactions in the periplasm.
Several proteins of the Tol/Pal system are required for group A colicin import into Escherichia coli. Colicin A interacts with TolA and TolB via distinct regions of its N-terminal domain. Both interactions are required for colicin translocation. Using in vivo and in vitro approaches, we show in this study that colicin A also interacts with a third component of the Tol/Pal system required for colicin import, TolR. This interaction is specific to colicins dependent on TolR for their translocation, strongly suggesting a direct involvement of the interaction in the colicin translocation step. TolR is anchored to the inner membrane by a single transmembrane segment and protrudes into the periplasm. The interaction involves part of the periplasmic domain of TolR and a small region of the colicin A N-terminal domain. This region and the other regions responsible for the interaction with TolA and TolB have been mapped precisely within the colicin A N-terminal domain and appear to be arranged linearly in the colicin sequence. Multiple contacts with periplasmic-exposed Tol proteins are therefore a general principle required for group A colicin translocation.
Journet
L
L
CNRS, LISM, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
Bouveret
E
E
Rigal
A
A
Lloubes
R
R
Lazdunski
C
C
Bénédetti
H
H
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D003087:Colicins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005557:Formaldehyde / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D019897:Periplasm / Q000378:metabolism*; D033903:Periplasmic Proteins; D010957:Plasmids / Q000235:genetics; D011233:Precipitin Tests; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D021381:Protein Transport
D001426:Bacterial Proteins; D003087:Colicins; D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D033903:Periplasmic Proteins; C062093:tolA protein, E coli; C062094:tolB protein, E coli; C060794:tolR protein, E coli; D005557:Formaldehyde