A beta strand lock exchange for signal transduction in TonB-dependent transducers on the basis of a common structural motif.
Transport of molecules larger than 600 Da across the outer membrane involves TonB-dependent receptors and TonB-ExbB-ExbD of the inner membrane. The transport is energy consuming, and involves direct interactions between a short N-terminal sequence of receptor, called the TonB box, and TonB. We solved the structure of the ferric pyoverdine (Pvd-Fe) outer membrane receptor FpvA from Pseudomonas aeruginosa in its apo form. Structure analyses show that residues of the TonB box are in a beta strand which interacts through a mixed four-stranded beta sheet with the periplasmic signaling domain involved in interactions with an inner membrane sigma regulator. In this conformation, the TonB box cannot form a four-stranded beta sheet with TonB. The FhuA-TonB or BtuB-TonB structures show that the TonB-FpvA interactions require a conformational change which involves a beta strand lock-exchange mechanism. This mechanism is compatible with movements of the periplasmic domain deduced from crystallographic analyses of FpvA, FpvA-Pvd, and FpvA-Pvd-Fe.
Brillet
Karl
K
Institut Gilbert-Laustriat, UMR7175 CNRS/Université Louis Pasteur, Strasbourg I, Département Récepteurs et Protéines Membranaires, Ecole Supérieure de Biotechnologie de Strasbourg, BP 10413, F-67412 Illkirch, France.
Journet
Laure
L
Célia
Hervé
H
Paulus
Laetitia
L
Stahl
Aude
A
Pattus
Franc
F
Cobessi
David
D
D020816:Amino Acid Motifs; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D019897:Periplasm / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D015398:Signal Transduction
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C082326:FpvA protein, Pseudomonas aeruginosa; D008565:Membrane Proteins; C057616:tonB protein, Bacteria