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 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 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.

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 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.

scholarly journals Influence of the TorD signal peptide chaperone on Tat-dependent protein translocation

2021 ◽  
Author(s):  
Umesh K Bageshwar ◽  
Antara DattaGupta ◽  
Siegfried M Musser
Keyword(s):  
Signal Peptide ◽  
Protein Translocation ◽  
Binding Interaction ◽  
Twin Arginine Translocation ◽  
Tat Pathway ◽  
Hand Off ◽  
Dependent Protein ◽  
Tat System ◽  
Folded Proteins ◽  
High Concentrations

The twin-arginine translocation (Tat) pathway transports folded proteins across energetic membranes. Numerous Tat substrates contain co-factors that are inserted before transport with the assistance of redox enzyme maturation proteins (REMPs), which bind to the signal peptide of precursor proteins. How signal peptides are transferred from a REMP to a binding site on the Tat receptor complex remains unknown. Since the signal peptide mediates both interactions, possibilities include: i) a coordinated hand-off mechanism; or ii) a diffusional search after REMP dissociation. We investigated the binding interaction between substrates containing the TorA signal peptide (spTorA) and its cognate REMP, TorD, and the effect of TorD on the in vitrotransport of such substrates. We found that Escherichia coli TorD is predominantly a monomer at low micromolar concentrations (dimerization KD > 50 M), and this monomer binds reversibly to spTorA (KD 1 M). While TorD binds to membranes (KD 100 nM), it has no apparent affinity for Tat translocons and it inhibits binding of a precursor substrate to the membrane. TorD has a minimal effect on substrate transport by the Tat system, being mildly inhibitory at high concentrations. These data are consistent with a model in which the REMP-bound signal peptide is shielded from recognition by the Tat translocon, and spontaneous dissociation of the REMP allows the substrate to engage the Tat machinery. Thus, the REMP does not assist with targeting to the Tat translocon, but rather temporarily shields the signal peptide.

scholarly journals Influence of the TorD signal peptide chaperone on Tat-dependent protein translocation

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0256715
Author(s):  
Umesh K. Bageshwar ◽  
Antara DattaGupta ◽  
Siegfried M. Musser
Keyword(s):  
Signal Peptide ◽  
Protein Translocation ◽  
Binding Interaction ◽  
Twin Arginine Translocation ◽  
Hand Off ◽  
Dependent Protein ◽  
Tat System ◽  
Folded Proteins ◽  
High Concentrations

The twin-arginine translocation (Tat) pathway transports folded proteins across energetic membranes. Numerous Tat substrates contain co-factors that are inserted before transport with the assistance of redox enzyme maturation proteins (REMPs), which bind to the signal peptide of precursor proteins. How signal peptides are transferred from a REMP to a binding site on the Tat receptor complex remains unknown. Since the signal peptide mediates both interactions, possibilities include: i) a coordinated hand-off mechanism; or ii) a diffusional search after REMP dissociation. We investigated the binding interaction between substrates containing the TorA signal peptide (spTorA) and its cognate REMP, TorD, and the effect of TorD on the in vitro transport of such substrates. We found that Escherichia coli TorD is predominantly a monomer at low micromolar concentrations (dimerization KD > 50 μM), and this monomer binds reversibly to spTorA (KD ≈ 1 μM). While TorD binds to membranes (KD ≈ 100 nM), it has no apparent affinity for Tat translocons and it inhibits binding of a precursor substrate to the membrane. TorD has a minimal effect on substrate transport by the Tat system, being mildly inhibitory at high concentrations. These data are consistent with a model in which the REMP-bound signal peptide is shielded from recognition by the Tat translocon, and spontaneous dissociation of the REMP allows the substrate to engage the Tat machinery. Thus, the REMP does not assist with targeting to the Tat translocon, but rather temporarily shields the signal peptide.

scholarly journals The Tat-dependent protein translocation pathway

2011 ◽  
Vol 2 (6) ◽  
pp. 507-523 ◽  
Author(s):  
Bo Hou ◽  
Thomas Brüser
Keyword(s):  
Protein Transport ◽  
Protein Translocation ◽  
Transport Systems ◽  
Binding Motif ◽  
Twin Arginine Translocation ◽  
Multiple Copies ◽  
Dependent Protein ◽  
Tat System ◽  
Folded Proteins ◽  
Polytopic Membrane Protein

AbstractThe twin-arginine translocation (Tat) pathway is found in bacteria, archaea, and plant chloroplasts, where it is dedicated to the transmembrane transport of fully folded proteins. These proteins contain N-terminal signal peptides with a specific Tat-system binding motif that is recognized by the transport machinery. In contrast to other protein transport systems, the Tat system consists of multiple copies of only two or three usually small (∼8–30 kDa) membrane proteins that oligomerize to two large complexes that transiently interact during translocation. Only one of these complexes includes a polytopic membrane protein, TatC. The other complex consists of TatA. Tat systems of plants, proteobacteria, and several other phyla contain a third component, TatB. TatB is evolutionarily and structurally related to TatA and usually forms tight complexes with TatC. Minimal two-component Tat systems lacking TatB are found in many bacterial and archaeal phyla. They consist of a ‘bifunctional’ TatA that also covers TatB functionalities, and a TatC. Recent insights into the structure and interactions of the Tat proteins have various important implications.

scholarly journals A Metzincin and TIMP-Like Protein Pair of a Phage Origin Sensitize Listeria monocytogenes to Phage Lysins and Other Cell Wall Targeting Agents

2021 ◽  
Vol 9 (6) ◽  
pp. 1323
Author(s):  
Etai Boichis ◽  
Nadejda Sigal ◽  
Ilya Borovok ◽  
Anat A. Herskovits
Keyword(s):  
Cell Wall ◽  
Listeria Monocytogenes ◽  
Mammalian Cells ◽  
Protein Pair ◽  
Growth Conditions ◽  
Wall Structure ◽  
Antibiotic Resistant ◽  
Extracellular Milieu ◽  
Virion Release ◽  
Genes Encoding

Infection of mammalian cells by Listeria monocytogenes (Lm) was shown to be facilitated by its phage elements. In a search for additional phage remnants that play a role in Lm’s lifecycle, we identified a conserved locus containing two XRE regulators and a pair of genes encoding a secreted metzincin protease and a lipoprotein structurally similar to a TIMP-family metzincin inhibitor. We found that the XRE regulators act as a classic CI/Cro regulatory switch that regulates the expression of the metzincin and TIMP-like genes under intracellular growth conditions. We established that when these genes are expressed, their products alter Lm morphology and increase its sensitivity to phage mediated lysis, thereby enhancing virion release. Expression of these proteins also sensitized the bacteria to cell wall targeting compounds, implying that they modulate the cell wall structure. Our data indicate that these effects are mediated by the cleavage of the TIMP-like protein by the metzincin, and its subsequent release to the extracellular milieu. While the importance of this locus to Lm pathogenicity remains unclear, the observation that this phage-associated protein pair act upon the bacterial cell wall may hold promise in the field of antibiotic potentiation to combat antibiotic resistant bacterial pathogens.

Integration host factor alleviates H-NS silencing of the Salmonella enterica serovar Typhimurium master regulator of SPI1, hilA

Microbiology ◽  
2011 ◽  
Vol 157 (9) ◽  
pp. 2504-2514 ◽  
Author(s):  
Mário H. Queiroz ◽  
Cristina Madrid ◽  
Sònia Paytubi ◽  
Carlos Balsalobre ◽  
Antonio Juárez
Keyword(s):  
Stationary Phase ◽  
Salmonella Enterica ◽  
Growth Conditions ◽  
Integration Host Factor ◽  
Band Shift ◽  
Global Regulators ◽  
Serovar Typhimurium ◽  
Associated Proteins ◽  
Transcription Data

Coordination of the expression of Salmonella enterica invasion genes on Salmonella pathogenicity island 1 (SPI1) depends on a complex circuit involving several regulators that converge on expression of the hilA gene, which encodes a transcriptional activator (HilA) that modulates expression of the SPI1 virulence genes. Two of the global regulators that influence hilA expression are the nucleoid-associated proteins Hha and H-NS. They interact and form a complex that modulates gene expression. A chromosomal transcriptional fusion was constructed to assess the effects of these modulators on hilA transcription under several environmental conditions as well as at different stages of growth. The results obtained showed that these proteins play a role in silencing hilA expression at both low temperature and low osmolarity, irrespective of the growth phase. H-NS accounts for the main repressor activity. At high temperature and osmolarity, H-NS-mediated silencing completely ceases when cells enter the stationary phase, and hilA expression is induced. Mutants lacking IHF did not induce hilA in cells entering the stationary phase, and this lack of induction was dependent on the presence of H-NS. Band-shift assays and in vitro transcription data showed that for hilA induction under certain growth conditions, IHF is required to alleviate H-NS-mediated silencing.

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