The Twin-Arginine Translocation System: A Novel Means of Transporting Folded Proteins in Chloroplasts and Bacteria

2000 ◽  
Vol 381 (2) ◽  
pp. 89-93 ◽  
Author(s):  
C. Robinson
Keyword(s):  
Escherichia Coli ◽  
Transport Proteins ◽  
Membrane Systems ◽  
Related System ◽  
Twin Arginine Translocation ◽  
System A ◽  
Unfolded State ◽  
Tat System ◽  
Folded Proteins ◽  
Unique Ability

Abstract Protein translocases have been characterised in several membrane systems and the translocation mechanisms have been shown to differ in critical respects. Nevertheless, the majority were believed to transport proteins only in a largely unfolded state, and this widespread characteristic was viewed as a likely evolutionary effort to minimise the diameter of translocation pore required. Within the last few years, however, studies on the chloroplast thylakoid membrane have revealed a novel class of protein translocase which possesses the apparently unique ability to transport fullyfolded proteins across a tightly sealed energytransducing membrane. A related system, (the twinarginine translocation, or Tat system) has now been characterised in the Escherichia coli plasma membrane and considerations of its substrate specificity again point to its involvement in the transport of folded proteins. The emerging data suggest a critical involvement in many membranes for the biogenesis of two types of globular protein: those that are obliged to fold prior to translocation, and those that fold too tightly or rapidly for other types of protein translocase to handle.

scholarly journals Contribution of the Twin Arginine Translocation System to the Virulence of Enterohemorrhagic Escherichia coli O157:H7

2003 ◽  
Vol 71 (9) ◽  
pp. 4908-4916 ◽  
Author(s):  
Nathalie Pradel ◽  
Changyun Ye ◽  
Valérie Livrelli ◽  
Jianguo Xu ◽  
Bernard Joly ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Immunoblot Analysis ◽  
Vero Cells ◽  
Soft Agar ◽  
Enterohemorrhagic Escherichia Coli ◽  
E Coli ◽  
Twin Arginine Translocation ◽  
Tat System ◽  
K 12

ABSTRACT Shiga toxin-producing Escherichia coli O157:H7 is a major food-borne infectious pathogen. In order to analyze the contribution of the twin arginine translocation (TAT) system to the virulence of E. coli O157:H7, we deleted the tatABC genes of the O157:H7 EDL933 reference strain. The mutant displayed attenuated toxicity on Vero cells and completely lost motility on soft agar plates. Further analyses revealed that the ΔtatABC mutation impaired the secretion of the Shiga toxin 1 (Stx1) and abolished the synthesis of H7 flagellin, which are two major known virulence factors of enterohemorrhagic E. coli O157:H7. Expression of the EDL933 stxAB 1 genes in E. coli K-12 conferred verotoxicity on this nonpathogenic strain. Remarkably, cytotoxicity assay and immunoblot analysis showed, for the first time, an accumulation of the holotoxin complex in the periplasm of the wild-type strain and that a much smaller amount of StxA1 and reduced verotoxicity were detected in the ΔtatC mutant cells. Together, these results establish that the TAT system of E. coli O157:H7 is an important virulence determinant of this enterohemorrhagic pathogen.

scholarly journals Inactivation of Rv2525c, a Substrate of the Twin Arginine Translocation (Tat) System of Mycobacterium tuberculosis, Increases β-Lactam Susceptibility and Virulence

2006 ◽  
Vol 188 (18) ◽  
pp. 6669-6679 ◽  
Author(s):  
Brigitte Saint-Joanis ◽  
Caroline Demangel ◽  
Mary Jackson ◽  
Priscille Brodin ◽  
Laurent Marsollier ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Biochemical Analysis ◽  
Species Conservation ◽  
Knockout Mutant ◽  
Orthologous Genes ◽  
Twin Arginine Translocation ◽  
Cell Wall Biogenesis ◽  
Tat System ◽  
Folded Proteins

ABSTRACT The twin arginine translocation (Tat) system is used by many bacteria to export fully folded proteins containing cofactors. Here, we show genetically that this system is essential for Mycobacterium tuberculosis, as the tatAC operon and tatB genes could be inactivated only in partially diploid strains. Using comparative genomics, the rv2525c gene of M. tuberculosis was identified as encoding a histidine-rich protein, with a twin arginine signal peptide, and orthologous genes were shown to be present in several but not all actinobacterial species. Conservation of this gene by Mycobacterium leprae, which has undergone reductive evolution, suggested an important role for rv2525c. An rv2525c knockout mutant was constructed, and biochemical analysis indicated that the mature Rv2525c protein is secreted. Upon exposure to antituberculous drugs, rv2525c expression is significantly up-regulated together with those of other genes involved in cell wall biogenesis. Phenotypic comparison of the mutant with the parental strain revealed an increase in susceptibility to some β-lactam antibiotics and, despite slower growth in vitro, enhanced virulence in both cellular and murine models of tuberculosis. The Tat system thus contributes in multiple ways to survival of the tubercle bacillus.

scholarly journals Channel crossing: how are proteins shipped across the bacterial plasma membrane?

2015 ◽  
Vol 370 (1679) ◽  
pp. 20150025 ◽  
Author(s):  
Ian Collinson ◽  
Robin A. Corey ◽  
William J. Allen
Keyword(s):  
Free Energy ◽  
Plasma Membrane ◽  
Atp Hydrolysis ◽  
Protein Translocation ◽  
Transmembrane Protein ◽  
Conducting Channel ◽  
Outstanding Problem ◽  
Unfolded State ◽  
Tat System ◽  
Folded Proteins

The structure of the first protein-conducting channel was determined more than a decade ago. Today, we are still puzzled by the outstanding problem of protein translocation—the dynamic mechanism underlying the consignment of proteins across and into membranes. This review is an attempt to summarize and understand the energy transducing capabilities of protein-translocating machines, with emphasis on bacterial systems: how polypeptides make headway against the lipid bilayer and how the process is coupled to the free energy associated with ATP hydrolysis and the transmembrane protein motive force. In order to explore how cargo is driven across the membrane, the known structures of the protein-translocation machines are set out against the background of the historic literature, and in the light of experiments conducted in their wake. The paper will focus on the bacterial general secretory (Sec) pathway (SecY-complex), and its eukaryotic counterpart (Sec61-complex), which ferry proteins across the membrane in an unfolded state, as well as the unrelated Tat system that assembles bespoke channels for the export of folded proteins.

scholarly journals Substrate-triggered position switching of TatA and TatB during Tat transport in Escherichia coli

Open Biology ◽  
2017 ◽  
Vol 7 (8) ◽  
pp. 170091 ◽  
Author(s):  
Johann Habersetzer ◽  
Kristoffer Moore ◽  
Jon Cherry ◽  
Grant Buchanan ◽  
Phillip J. Stansfeld ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Binding Sites ◽  
Protein Transport ◽  
Cytoplasmic Membrane ◽  
Polar Cluster ◽  
Additional Sequence ◽  
Tat System ◽  
Folded Proteins ◽  
Related Proteins

The twin-arginine protein transport (Tat) machinery mediates the translocation of folded proteins across the cytoplasmic membrane of prokaryotes and the thylakoid membrane of plant chloroplasts. The Escherichia coli Tat system comprises TatC and two additional sequence-related proteins, TatA and TatB. The active translocase is assembled on demand, with substrate-binding at a TatABC receptor complex triggering recruitment and assembly of multiple additional copies of TatA; however, the molecular interactions mediating translocase assembly are poorly understood. A ‘polar cluster’ site on TatC transmembrane (TM) helix 5 was previously identified as binding to TatB. Here, we use disulfide cross-linking and molecular modelling to identify a new binding site on TatC TM helix 6, adjacent to the polar cluster site. We demonstrate that TatA and TatB each have the capacity to bind at both TatC sites, however in vivo this is regulated according to the activation state of the complex. In the resting-state system, TatB binds the polar cluster site, with TatA occupying the TM helix 6 site. However when the system is activated by overproduction of a substrate, TatA and TatB switch binding sites. We propose that this substrate-triggered positional exchange is a key step in the assembly of an active Tat translocase.

scholarly journals The Twin Arginine Translocation System Is Essential for Virulence of Yersinia pseudotuberculosis

2006 ◽  
Vol 74 (3) ◽  
pp. 1768-1776 ◽  
Author(s):  
Moa Lavander ◽  
Solveig K. Ericsson ◽  
Jeanette E. Bröms ◽  
Åke Forsberg
Keyword(s):  
Type Iii Secretion ◽  
Yersinia Pseudotuberculosis ◽  
Acid Resistance ◽  
Infection Model ◽  
Type Iii ◽  
Twin Arginine Translocation ◽  
Mouse Infection Model ◽  
Tat System ◽  
Folded Proteins

ABSTRACT Yersinia species pathogenic to humans have been extensively characterized with respect to type III secretion and its essential role in virulence. This study concerns the twin arginine translocation (Tat) pathway utilized by gram-negative bacteria to secrete folded proteins across the bacterial inner membrane into the periplasmic compartment. We have shown that the Yersinia Tat system is functional and required for motility and contributes to acid resistance. A Yersinia pseudotuberculosis mutant strain with a disrupted Tat system (tatC) was, however, not affected in in vitro growth or more susceptible to high osmolarity, oxidative stress, or high temperature, nor was it impaired in type III secretion. Interestingly, the tatC mutant was severely attenuated via both the oral and intraperitoneal routes in the systemic mouse infection model and highly impaired in colonization of lymphoid organs like Peyer's patches and the spleen. Our work highlights that Tat secretion plays a key role in the virulence of Y. pseudotuberculosis.

scholarly journals Substrate-triggered position-switching of TatA and TatB is an essential step in the Escherichia coli Tat protein export pathway

2017 ◽  
Author(s):  
Johann Habersetzer ◽  
Kristoffer Moore ◽  
Jon Cherry ◽  
Grant Buchanan ◽  
Phillip Stansfeld ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Binding Sites ◽  
Protein Transport ◽  
Transmembrane Helix ◽  
Tat Protein ◽  
Disulfide Crosslinking ◽  
Additional Sequence ◽  
Tat System ◽  
Folded Proteins ◽  
Related Proteins

AbstractThe twin arginine protein transport (Tat) machinery mediates the translocation of folded proteins across the cytoplasmic membrane of prokaryotes and the thylakoid membrane of plant chloroplasts. The Escherichia coli Tat system comprises TatC and two additional sequence-related proteins, TatA and TatB. Here we use disulfide crosslinking and molecular modelling to show there are two binding sites for TatA/B proteins on TatC. TatA and TatB are each able to occupy both sites if they are the only TatA/B protein present. However, under resting conditions the sites are differentially occupied with TatB occupying the ‘polar cluster’ site while TatA binds adjacently at the TatC transmembrane helix 6 binding site. When the Tat system is activated by the overproduction of a substrate, TatA and TatB switch their binding sites. We propose that this substrate-triggered positional exchange is a key step in the assembly of an active Tat translocase.

scholarly journals Twin-arginine translocation (Tat) mutants in Salmonella enterica serovar Typhimurium have increased susceptibility to cell wall targeting antibiotics

FEMS Microbes ◽  
2021 ◽  
Vol 2 ◽  
Author(s):  
Adrienne M Brauer ◽  
Alexandra R Rogers ◽  
Jeremy R Ellermeier
Keyword(s):  
Cell Wall ◽  
Anaerobic Respiration ◽  
Growth Curves ◽  
Growth Conditions ◽  
Twin Arginine Translocation ◽  
Serovar Typhimurium ◽  
Plate Counts ◽  
Protein Secretion System ◽  
Tat System ◽  
Folded Proteins

ABSTRACT The twin-arginine translocation (Tat) system is a protein secretion system that is conserved in bacteria, archaea and plants. In Gram-negative bacteria, it is required for the export of folded proteins from the cytoplasm to the periplasm. There are 30 experimentally verified Tat substrates in Salmonella, including hydrogenase subunits, enzymes required for anaerobic respiration and enzymes involved in peptidoglycan remodeling during cell division. Multiple studies have demonstrated the susceptibility of tat mutants to antimicrobial compounds such as SDS and bile; however, in this work, we use growth curves and viable plate counts to demonstrate that cell wall targeting antibiotics (penicillins, carbapenems, cephalosporins and fosfomycin) have increased killing against a Δtat strain. Further, we demonstrate that this increased killing is primarily due to defects in translocation of critical Tat substrates: MepK, AmiA, AmiC and SufI. Finally, we show that a ΔhyaAB ΔhybABC ΔhydBC strain has an altered ΔΨ that impacts proper secretion of critical Tat substrates in aerobic growth conditions.

scholarly journals Engineering a super-secreting strain of Escherichia coli by directed co-evolution of the multiprotein Tat translocation machinery

2021 ◽  
Author(s):  
May N. Taw ◽  
Mingji Li ◽  
Daniel Kim ◽  
Mark A. Rocco ◽  
Dujduan Waraho-Zhmayev ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Recombinant Proteins ◽  
Genetic Manipulation ◽  
Value Added ◽  
Heterologous Proteins ◽  
Sec Pathway ◽  
Twin Arginine Translocation ◽  
Transit Times ◽  
Tat Pathway ◽  
Folded Proteins

AbstractEscherichia coli remains one of the preferred hosts for biotechnological protein production due to its robust growth in culture and ease of genetic manipulation. It is often desirable to export recombinant proteins into the periplasmic space for reasons related to proper disulfide bond formation, prevention of aggregation and proteolytic degradation, and ease of purification. One such system for expressing heterologous secreted proteins is the twin-arginine translocation (Tat) pathway, which has the unique advantage of delivering correctly folded proteins into the periplasm. However, transit times for proteins through the Tat translocase, comprised of the TatABC proteins, are much longer than for passage through the SecYEG pore, the translocase associated with the more widely utilized Sec pathway. To date, a high protein flux through the Tat pathway has yet to be demonstrated. To address this shortcoming, we employed a directed co-evolution strategy to isolate mutant Tat translocases for their ability to deliver higher quantities of heterologous proteins into the periplasm. Three super-secreting translocases were selected that each exported a panel of recombinant proteins at levels that were significantly greater than that observed for wildtype TatABC or SecYEG translocases. Interestingly, all three of the evolved Tat translocases exhibited quality control suppression, suggesting that increased translocation flux was gained by relaxation of substrate proofreading. Overall, our discovery of highly efficient translocase variants paves the way for the use of the Tat system as a powerful complement to the Sec pathway for secreted production of both commodity and high value-added proteins.

The archaeal twin-arginine translocation pathway

2003 ◽  
Vol 31 (3) ◽  
pp. 686-689 ◽  
Author(s):  
G.W. Hutcheon ◽  
A. Bolhuis
Keyword(s):  
Cytoplasmic Membrane ◽  
Small Subset ◽  
Twin Arginine Translocation ◽  
Moderate Number ◽  
Cytoplasmic Proteins ◽  
Tat Pathway ◽  
Tat System ◽  
Main Components ◽  
Unique Ability

The twin-arginine translocation (Tat) pathway is a system with the unique ability to export proteins in a fully folded conformation. Its main components are TatA, TatB and TatC, all of which are required for Tat-dependent export. The Tat pathway is found in several Archaea, and in most of them a moderate number of predicted Tat-dependent substrates are present. Putative substrates include those binding cofactors such as iron–sulphur clusters and molybdopterin. In these Archaea, the role of the Tat pathway seems to be similar to that of bacteria: the export of a small subset of proteins that fold before translocation across the cytoplasmic membrane. The exception to this is the Tat system of the halophilic archaeon Halobacterium sp. NRC-1. In this organism, the majority of extra-cytoplasmic proteins are predicted to use the Tat pathway, which is, most likely, a specific adaptation to its particular lifestyle in highly saline conditions.

scholarly journals Functional Tat Transport of Unstructured, Small, Hydrophilic Proteins

2007 ◽  
Vol 282 (46) ◽  
pp. 33257-33264 ◽  
Author(s):  
Silke Richter ◽  
Ute Lindenstrauss ◽  
Christian Lücke ◽  
Richard Bayliss ◽  
Thomas Brüser
Keyword(s):  
Protein Translocation ◽  
Signal Sequence ◽  
Hydrophobic Surface ◽  
Physiological Data ◽  
Nuclear Pore ◽  
Hydrophobic Core ◽  
Twin Arginine Translocation ◽  
Surface Patches ◽  
Tat System ◽  
Folded Proteins

The twin-arginine translocation (Tat) system is a protein translocation system that is adapted to the translocation of folded proteins across biological membranes. An understanding of the folding requirements for Tat substrates is of fundamental importance for the elucidation of the transport mechanism. We now demonstrate for the first time Tat transport for fully unstructured proteins, using signal sequence fusions to naturally unfolded FG repeats from the yeast Nsp1p nuclear pore protein. The transport of unfolded proteins becomes less efficient with increasing size, consistent with only a single interaction between the system and the substrate. Strikingly, the introduction of six residues from the hydrophobic core of a globular protein completely blocked translocation. Physiological data suggest that hydrophobic surface patches abort transport at a late stage, most likely by membrane interactions during transport. This study thus explains the observed restriction of the Tat system to folded globular proteins on a molecular level.

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