The Tol/Pal system function requires an interaction between the C-terminal domain of TolA and the N-terminal domain of TolB.
The Tol/Pal system of Escherichia coli is composed of the YbgC, TolQ, TolA, TolR, TolB, Pal and YbgF proteins. It is involved in maintaining the integrity of the outer membrane, and is required for the uptake of group A colicins and DNA of filamentous bacteriophages. To identify new interactions between the components of the Tol/Pal system and gain insight into the mechanism of colicin import, we performed a yeast two-hybrid screen using the different components of the Tol/Pal system and colicin A. Using this system, we confirmed the already known interactions and identified several new interactions. TolB dimerizes and the periplasmic domain of TolA interacts with YbgF and TolB. Our results indicate that the central domain of TolA (TolAII) is sufficient to interact with YbgF, that the C-terminal domain of TolA (TolAIII) is sufficient to interact with TolB, and that the amino terminal domain of TolB (D1) is sufficient to bind TolAIII. The TolA/TolB interaction was confirmed by cross-linking experiments on purified proteins. Moreover, we show that the interaction between TolA and TolB is required for the uptake of colicin A and for the membrane integrity. These results demonstrate that the TolA/TolB interaction allows the formation of a trans-envelope complex that brings the inner and outer membranes in close proximity.
Walburger
Anne
A
Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Biologie Structurale et Microbiologie, CNRS 31, Chemin Joseph Aiguier, Marseille, France.
Lazdunski
Claude
C
Corda
Yves
Y
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics; D001692:Biological Transport; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000648:ultrastructure; D003087:Colicins / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000494:pharmacology / Q000502:physiology*; D005557:Formaldehyde / Q000494:pharmacology; D008074:Lipoproteins / Q000737:chemistry / Q000502:physiology; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry / Q000494:pharmacology / Q000502:physiology*; D016296:Mutagenesis; D010457:Peptidoglycan / Q000737:chemistry; D016133:Polymerase Chain Reaction; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D011509:Proteoglycans; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D020798:Two-Hybrid System Techniques; D000099160:LexA Repressor Protein
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D003087:Colicins; D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D005557:Formaldehyde; D008074:Lipoproteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D010457:Peptidoglycan; D011509:Proteoglycans; D011993:Recombinant Fusion Proteins; D012697:Serine Endopeptidases; D012967:Sodium Dodecyl Sulfate; D000099160:LexA Repressor Protein; C031163:ExcC protein, E coli; C459860:YbgF protein, E coli; C062093:tolA protein, E coli; C060792:tolQ protein, E coli; C060794:tolR protein, E coli; C069988:PplA protein, Legionella pneumophila