E. Amann, J. Brosius, and M. Ptashne, Vectors bearing a hybrid trp-lac promoter useful for regulated expression of cloned genes in Escherichia coli, Gene, vol.25, issue.2-3, pp.167-178, 1983.
DOI : 10.1016/0378-1119(83)90222-6

R. Lutz and H. Bujard, Independent and tight regulation of transcriptional units in 279, 1997.

A. Skerra, Use of the tetracycline promoter for the tightly regulated production of a murine antibody fragment in Escherichia coli, Gene, vol.151, issue.1-2, pp.131-135, 1994.
DOI : 10.1016/0378-1119(94)90643-2

L. Guzman, D. Belin, M. Carson, and J. Beckwith, Tight regulation, modulation, and high-level expression by vectors containing the arabinose PBAD promoter., Journal of Bacteriology, vol.177, issue.14, pp.4121-287, 1995.
DOI : 10.1128/jb.177.14.4121-4130.1995

A. Haldimann, L. Daniels, and B. Wanner, Use of new methods for construction of tightly 289 regulated arabinose and rhamnose promoter fusions in studies of the Escherichia coli phosphate 290 regulon, J Bacteriol, vol.180, pp.1277-1286, 1998.

S. Balzer, V. Kucharova, J. Megerle, R. Lale, T. Brautaset et al., A comparative 292 analysis of the properties of regulated promoter systems commonly used for recombinant gene 293 expression in Escherichia coli. Microb Cell Fact, p.26, 2013.

F. Studier, Use of bacteriophage T7 lysozyme to improve an inducible T7 expression system, Journal of Molecular Biology, vol.219, issue.1, pp.37-44, 1991.
DOI : 10.1016/0022-2836(91)90855-Z

J. Gier, Optimizing membrane protein overexpression in the Escherichia coli strain 298, 2012.

J. Dubendorff and F. Studier, Controlling basal expression in an inducible T7 expression system by blocking the target T7 promoter with lac repressor, Journal of Molecular Biology, vol.219, issue.1, pp.45-59, 1991.
DOI : 10.1016/0022-2836(91)90856-2

F. Bernhard, Preparative scale expression of membrane proteins in Escherichia coli-based 303 continuous exchange cell-free systems, Nat Protoc, vol.2, pp.2945-2957, 2007.

G. Guihard, P. Boulanger, H. Bénédetti, R. Lloubes, M. Besnard et al., Colicin A 305 and the Tol proteins involved in its translocation are preferentially located in the contact sites 306 between the inner and outer membranes of Escherichia coli cells, J Biol Chem, vol.269, pp.5874-5880, 1994.

E. Cascales, R. Lloubes, and J. Sturgis, The TolQ-TolR proteins energize TolA and share homologies with the flagellar motor proteins ???MotA-MotB, Molecular Microbiology, vol.180, issue.3, pp.795-807, 2001.
DOI : 10.1073/pnas.95.11.6436

W. , L. R. Buchanan, and S. , Structural insight into the role of the Ton complex in 311 energy transduction, Nature, vol.538, pp.60-65, 2016.

A. Pramanik, F. Zhang, H. Schwarz, F. Schreiber, and V. Braun, Forms a Stable Oligomer, Biochemistry, vol.49, issue.40, pp.8721-8728, 2010.
DOI : 10.1021/bi101143y

A. Pramanik, W. Hauf, J. Hoffmann, M. Cernescu, B. Brutschy et al., As Revealed by LILBID Mass Spectrometry, Biochemistry, vol.50, issue.41, pp.8950-8956, 2011.
DOI : 10.1021/bi2008195

J. Coulton, Coordinated rearrangements between cytoplasmic and periplasmic domains 319 of the membrane protein complex ExbB-ExbD of Escherichia coli, Structure, vol.22, pp.791-797, 2014.

H. Low, F. Gubellini, A. Rivera-calzada, N. Braun, S. Connery et al., Structure of a type IV secretion system, Nature, vol.2, issue.7497, pp.508-550, 2014.
DOI : 10.7554/eLife.00792

A. Desmyter, B. Bardiaux, A. Dujeancourt, A. Roussel, C. Cambillau et al., Biogenesis and structure of a type VI secretion membrane core complex, Nature, vol.331, issue.332, pp.555-560, 2015.
URL : https://hal.archives-ouvertes.fr/hal-01778556

J. Bakelar, S. Buchanan, and N. Noinaj, The structure of the ??-barrel assembly machinery complex, Science, vol.372, issue.3, pp.180-186, 2016.
DOI : 10.1016/j.jmb.2007.05.022

S. Tabor and C. Richardson, A bacteriophage T7 RNA polymerase/promoter system for controlled exclusive expression of specific genes., Proceedings of the National Academy of Sciences, vol.82, issue.4, pp.1074-1078, 1985.
DOI : 10.1073/pnas.82.4.1074

F. Studier and B. Moffatt, Use of bacteriophage T7 RNA polymerase to direct selective high-level expression of cloned genes, Journal of Molecular Biology, vol.189, issue.1, pp.113-130, 1986.
DOI : 10.1016/0022-2836(86)90385-2

S. Stuchlík and J. Turna, Overexpression of the FNR protein ofEscherichia coli with T7 expression system, Folia Microbiologica, vol.59, issue.6, pp.601-604, 1998.
DOI : 10.1007/BF02816375

A. Doherty, B. Connolly, and A. Worrall, Overproduction of the toxic protein, p.348, 1993.

F. Van-den-ent and J. Löwe, RF cloning: A restriction-free method for inserting target genes into plasmids, Journal of Biochemical and Biophysical Methods, vol.67, issue.1, pp.67-74, 2006.
DOI : 10.1016/j.jbbm.2005.12.008

J. Jeong, H. Yim, J. Ryu, H. Lee, J. Lee et al., One-step sequence-and 353, 2012.

H. Bénédetti, C. Lazdunski, and R. Lloubes, Protein import into Escherichia coli: colicins A 356 and E1 interact with a component of their translocation system, EMBO J, vol.10, 1989.

R. Derouiche, H. Bénédetti, J. Lazzaroni, C. Lazdunski, and R. Lloubes, Protein complex within Escherichia coli inner membrane. TolA N-terminal domain interacts with TolQ and TolR proteins, Journal of Biological Chemistry, vol.270, issue.19, pp.11078-11084, 1995.
DOI : 10.1074/jbc.270.19.11078

A. Konovalova and T. Silhavy, Outer membrane lipoprotein biogenesis: Lol is not the end, Philosophical Transactions of the Royal Society B: Biological Sciences, vol.176, issue.1679, p.1679, 2015.
DOI : 10.1128/JB.05849-11
URL : http://rstb.royalsocietypublishing.org/content/royptb/370/1679/20150030.full.pdf

M. We-would-like-to-thank, L. Petiti, and H. Houot, Célia and D. Duché for careful reading, ED and 368 RL are are funded by the Centre National de la Recherche Scientifique, the

. Duet-vector, (c) Schemes representing the protein constructs, the sub-domain boundaries and 378 some indicated characteristics (TM, transmembrane segments; SP, signal peptide