Twin-arginine translocase may have a role in the chaperone function of NarJ from Escherichia coli

AbstractThe twin arginine translocation (Tat) system is an integral membrane protein complex that accomplishes the remarkable feat of transporting large, fully-folded polypeptides across the inner membrane of bacteria, into the periplasm. In Escherichia coli Tat is comprised of three membrane proteins: TatA, TatB and TatC. How these proteins arrange themselves in the inner membrane to permit passage of Tat substrates, whilst maintaining membrane integrity, is still poorly understood. TatA is the most abundant component of this complex and facilitates assembly of the transport mechanism. We have utilised immunogold labelling in combination with array tomography to gain insight into the localisation and distribution of the TatA protein in E. coli cells. We show that TatA exhibits a uniform distribution throughout the inner membrane of E. coli and that altering the expression of TatBC shows a previously uncharacterised distribution of TatA in the inner membrane. Array tomography was used to provide our first insight into this altered distribution of TatA in 3D space, revealing that this protein forms linear clusters in the inner membrane of E. coli upon increased expression of TatBC. This is the first indication that TatA organisation in the inner membrane alters in response to changes in Tat subunit stoichiometry.Summary statementThe volumetric electron-microscopy technique, array tomography, revealed a novel distribution of TatA protein (from the twin arginine translocase complex), in Escherichia coli.

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Cysteine Scanning Mutagenesis and Topological Mapping of the Escherichia coli Twin-Arginine Translocase TatC Component

Journal of Bacteriology ◽

10.1128/jb.00647-07 ◽

2007 ◽

Vol 189 (15) ◽

pp. 5482-5494 ◽

Cited By ~ 35

Author(s):

Claire Punginelli ◽

Bárbara Maldonado ◽

Sabine Grahl ◽

Rachael Jack ◽

Meriem Alami ◽

...

Keyword(s):

Escherichia Coli ◽

Transmembrane Domain ◽

Protein Translocation ◽

Tat Protein ◽

Transmembrane Helices ◽

Dependent Protein ◽

Cross Links ◽

Twin Arginine Translocase ◽

Cysteine Scanning Mutagenesis ◽

Polytopic Membrane Protein

ABSTRACT The TatC protein is an essential component of the Escherichia coli twin-arginine (Tat) protein translocation pathway. It is a polytopic membrane protein that forms a complex with TatB, together acting as the receptor for Tat substrates. In this study we have constructed 57 individual cysteine substitutions throughout the protein. Each of the substitutions resulted in a TatC protein that was competent to support Tat-dependent protein translocation. Accessibility studies with membrane-permeant and -impermeant thiol-reactive reagents demonstrated that TatC has six transmembrane helices, rather than the four suggested by a previous study (K. Gouffi, C.-L. Santini, and L.-F. Wu, FEBS Lett. 525:65-70, 2002). Disulfide cross-linking experiments with TatC proteins containing single cysteine residues showed that each transmembrane domain of TatC was able to interact with the same domain from a neighboring TatC protein. Surprisingly, only three of these cysteine variants retained the ability to cross-link at low temperatures. These results are consistent with the likelihood that most of the disulfide cross-links are between TatC proteins in separate TatBC complexes, suggesting that TatC is located on the periphery of the complex.

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Redox-regulated chaperone function and conformational changes of Escherichia coli Hsp33

FEBS Letters ◽

10.1016/s0014-5793(01)02074-9 ◽

2001 ◽

Vol 489 (1) ◽

pp. 19-24 ◽

Cited By ~ 25

Author(s):

B Raman ◽

L.V Siva Kumar ◽

T Ramakrishna ◽

Ch Mohan Rao

Keyword(s):

Escherichia Coli ◽

Conformational Changes ◽

Chaperone Function

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Role of FtsEX in Cell Division of Escherichia coli: Viability of ftsEX Mutants Is Dependent on Functional SufI or High Osmotic Strength

Journal of Bacteriology ◽

10.1128/jb.01347-06 ◽

2006 ◽

Vol 189 (1) ◽

pp. 98-108 ◽

Cited By ~ 70

Author(s):

Manjula Reddy

Keyword(s):

Escherichia Coli ◽

Cell Division ◽

Salt Transport ◽

High Osmolarity ◽

Growth Defects ◽

Ring Assembly ◽

Multiple Copies ◽

Z Ring ◽

Twin Arginine Translocase ◽

The Stability

ABSTRACT In Escherichia coli, at least 12 proteins, FtsZ, ZipA, FtsA, FtsE/X, FtsK, FtsQ, FtsL, FtsB, FtsW, FtsI, FtsN, and AmiC, are known to localize to the septal ring in an interdependent and sequential pathway to coordinate the septum formation at the midcell. The FtsEX complex is the latest recruit of this pathway, and unlike other division proteins, it is shown to be essential only on low-salt media. In this study, it is shown that ftsEX null mutations are not only salt remedial but also osmoremedial, which suggests that FtsEX may not be involved in salt transport as previously thought. Increased coexpression of cell division proteins FtsQ-FtsA-FtsZ or FtsN alone restored the growth defects of ftsEX mutants. ftsEX deletion exacerbated the defects of most of the mutants affected in Z ring localization and septal assembly; however, the ftsZ84 allele was a weak suppressor of ftsEX. The viability of ftsEX mutants in high-osmolarity conditions was shown to be dependent on the presence of a periplasmic protein, SufI, a substrate of twin-arginine translocase. In addition, SufI in multiple copies could substitute for the functions of FtsEX. Taken together, these results suggest that FtsE and FtsX are absolutely required for the process of cell division in conditions of low osmotic strength for the stability of the septal ring assembly and that, during high-osmolarity conditions, the FtsEX and SufI functions are redundant for this essential process.

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Chaperone function of FkpA, a heat shock prolyl isomerase, in the periplasm of Escherichia coli

Molecular Microbiology ◽

10.1046/j.1365-2958.2001.02250.x ◽

2001 ◽

Vol 39 (1) ◽

pp. 199-210 ◽

Cited By ~ 108

Author(s):

Jean-Philippe Arié ◽

Nathalie Sassoon ◽

Jean-Michel Betton

Keyword(s):

Escherichia Coli ◽

Heat Shock ◽

Prolyl Isomerase ◽

Chaperone Function

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Effect of C-terminal truncation on the molecular chaperone function and dimerization of Escherichia coli trigger factor

Biochimie ◽

10.1016/j.biochi.2005.11.006 ◽

2006 ◽

Vol 88 (6) ◽

pp. 613-619 ◽

Cited By ~ 14

Author(s):

Li-Ling Zeng ◽

Ling Yu ◽

Zhen-Yu Li ◽

Sarah Perrett ◽

Jun-Mei Zhou

Keyword(s):

Escherichia Coli ◽

Molecular Chaperone ◽

Trigger Factor ◽

Chaperone Function

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Directed evolution of SecB chaperones toward toxin-antitoxin systems

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1710456114 ◽

2017 ◽

Vol 114 (47) ◽

pp. 12584-12589 ◽

Cited By ~ 6

Author(s):

Ambre Julie Sala ◽

Patricia Bordes ◽

Sara Ayala ◽

Nawel Slama ◽

Samuel Tranier ◽

...

Keyword(s):

Escherichia Coli ◽

Mycobacterium Tuberculosis ◽

Directed Evolution ◽

Substrate Binding ◽

Family Members ◽

Protein Export ◽

Adaptation To Stress ◽

Bacterial Adaptation ◽

Chaperone Function ◽

Binding Surface

SecB chaperones assist protein export in bacteria. However, certain SecB family members have diverged to become specialized toward the control of toxin-antitoxin (TA) systems known to promote bacterial adaptation to stress and persistence. In such tripartite TA-chaperone (TAC) systems, the chaperone was shown to assist folding and to prevent degradation of its cognate antitoxin, thus facilitating inhibition of the toxin. Here, we used both the export chaperone SecB ofEscherichia coliand the tripartite TAC system ofMycobacterium tuberculosisas a model to investigate how generic chaperones can specialize toward the control of TA systems. Through directed evolution of SecB, we have identified and characterized mutations that specifically improve the ability of SecB to control our model TA system without affecting its function in protein export. Such a remarkable plasticity of SecB chaperone function suggests that its substrate binding surface can be readily remodeled to accommodate specific clients.

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Effects of the twin-arginine translocase on the structure and antimicrobial susceptibility of Escherichia coli biofilms

Canadian Journal of Microbiology ◽

10.1139/w05-048 ◽

2005 ◽

Vol 51 (8) ◽

pp. 671-683 ◽

Cited By ~ 10

Author(s):

Joe J Harrison ◽

Howard Ceri ◽

Erin A Badry ◽

Nicole J Roper ◽

Kerry L Tomlin ◽

...

Keyword(s):

Escherichia Coli ◽

Biofilm Formation ◽

Type Strain ◽

Wild Type Strain ◽

Wild Type ◽

Planktonic Cells ◽

E Coli ◽

Minimal Media ◽

Twin Arginine Translocase ◽

Biofilm Structure

In this descriptive study, we used Escherichia coli twin-arginine translocase (tat) mutants to distinguish antibiotic tolerance from the formation of mature biofilm structure. Biofilm formation by wild-type and Δtat strains of E. coli was evaluated using viable cell counts, scanning electron microscopy, and confocal laser-scanning microscopy. Escherichia coli Δtat mutants had an impaired ability to form biofilms when grown in rich or minimal media. These mutants produced disorganized layers and cell aggregates with significantly decreased cell density relative to the wild-type strain. In contrast, wild-type E. coli grown under similar test conditions formed highly structured, surface-adherent communities. We thus determined if this decreased biofilm formation by E. coli Δtat mutants may result in lowered tolerance to antimicrobials. When grown in rich media, planktonic Δtat mutants were hypersensitive to some metals, detergents, and antibiotics. However, the corresponding biofilms were about as resilient as the wild-type strain. In contrast, both planktonic cells and biofilms of the ΔtatABC strain grown in minimal media were hypersensitive to many antimicrobials. Remarkably, these biofilms remained up to 365 times more tolerant to β-lactams than corresponding planktonic cells. Our data suggest that the twin-arginine translocase may play a contributing role in the antimicrobial tolerance, structural organization, and formation of mature E. coli biofilms under nutrient-limited conditions. However, the high tolerance of the ΔtatABC strain to bactericidal concentrations of antimicrobials indicates that mature biofilm structure may not be required for surface-adherent E. coli to survive exposure to these lethal factors.Key words: biofilm structure, twin-arginine translocase (tat), Escherichia coli, antimicrobial susceptibility/tolerance.

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