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Energetics of colicin import revealed by genetic cross-complementation between the Tol and Ton systems

Abstract : Colicins are bacterial toxins that parasitize OM (outer membrane) receptors to bind to the target cells, use an import system to translocate through the cell envelope and then kill sensitive cells. Colicins classified as group A (colicins A, E1–E9, K and N) use the Tol system (TolA, TolB, TolQ and TolR), whereas group B colicins (colicins B, D, Ia, M and 5) use the ExbB–ExbD–TonB system. Genetic evidence has suggested that TolQ and ExbB, as well as TolR and ExbD, are interchangeable, whereas this is not possible with TolA and TonB. Early reports indicated that group B colicin uptake requires energy input, whereas no energy was necessary for the uptake of the pore-forming colicin A. Furthermore, energy is required to dissociate the complex formed with colicin E9 and its cognate immunity protein during the import process. In the present paper, we detail the functional phenotypes and colicin-sensitivity results obtained in tolQ and exbB mutants and cross-complementation data of amino acid substitutions that lie within ExbB or TolQ TMHs (transmembrane helices). We also discuss on a specific phenotype that corresponds to group A colicin-sensitivity associated with a non-functional Tol system.
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https://hal-amu.archives-ouvertes.fr/hal-03274792
Contributor : Eric Cascales Connect in order to contact the contributor
Submitted on : Wednesday, June 30, 2021 - 2:24:17 PM
Last modification on : Wednesday, October 27, 2021 - 10:00:08 AM

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Roland Lloubès, Emilie Goemaere, Xiang Zhang, E. Cascales, Denis Duché. Energetics of colicin import revealed by genetic cross-complementation between the Tol and Ton systems. Biochemical Society Transactions, Portland Press, 2012, 40 (6), pp.1480-1485. ⟨10.1042/BST20120181⟩. ⟨hal-03274792⟩

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