scholarly journals Role of the Twin-Arginine Translocation Pathway in Staphylococcus

2009 ◽  
Vol 191 (19) ◽  
pp. 5921-5929 ◽  
Author(s):  
Lalitha Biswas ◽  
Raja Biswas ◽  
Christiane Nerz ◽  
Knut Ohlsen ◽  
Martin Schlag ◽  
...  
Keyword(s):  
Functional Unit ◽  
Signal Sequence ◽  
Protein A ◽  
Mouse Kidney ◽  
Deletion Mutants ◽  
Twin Arginine Translocation ◽  
High Affinity ◽  
Tat Pathway ◽  
First Time

ABSTRACT In Staphylococcus, the twin-arginine translocation (Tat) pathway is present only in some species and is composed of TatA and TatC. The tatAC operon is associated with the fepABC operon, which encodes homologs to an iron-binding lipoprotein, an iron-dependent peroxidase (FepB), and a high-affinity iron permease. The FepB protein has a typical twin-arginine (RR) signal peptide. The tat and fep operons constitute an entity that is not present in all staphylococcal species. Our analysis was focused on Staphylococcus aureus and S. carnosus strains. Tat deletion mutants (ΔtatAC) were unable to export active FepB, indicating that this enzyme is a Tat substrate. When the RR signal sequence from FepB was fused to prolipase and protein A, their export became Tat dependent. Since no other protein with a Tat signal could be detected, the fepABC-tatAC genes comprise not only a genetic but also a functional unit. We demonstrated that FepABC drives iron import, and in a mouse kidney abscess model, the bacterial loads of ΔtatAC and Δtat-fep mutants were decreased. For the first time, we show that the Tat pathway in S. aureus is functional and serves to translocate the iron-dependent peroxidase FepB.

scholarly journals Phage Shock Protein PspA of Escherichia coli Relieves Saturation of Protein Export via the Tat Pathway

2004 ◽  
Vol 186 (2) ◽  
pp. 366-373 ◽  
Author(s):  
Matthew P. DeLisa ◽  
Philip Lee ◽  
Tracy Palmer ◽  
George Georgiou
Keyword(s):  
Genomic Library ◽  
Protein Translocation ◽  
Signal Sequence ◽  
Protein A ◽  
Homologous Proteins ◽  
Gene Encoding ◽  
Protein Precursor ◽  
Twin Arginine Translocation ◽  
Tat Pathway

ABSTRACT Overexpression of either heterologous or homologous proteins that are routed to the periplasm via the twin-arginine translocation (Tat) pathway results in a block of export and concomitant accumulation of the respective protein precursor in the cytoplasm. Screening of a plasmid-encoded genomic library for mutants that confer enhanced export of a TorA signal sequence (ssTorA)-GFP-SsrA fusion protein, and thus result in higher cell fluorescence, yielded the pspA gene encoding phage shock protein A. Coexpression of pspA relieved the secretion block observed with ssTorA-GFP-SsrA or upon overexpression of the native Tat proteins SufI and CueO. A similar effect was observed with the Synechocystis sp. strain PCC6803 PspA homologue, VIPP1, indicating that the role of PspA in Tat export may be phylogenetically conserved. Mutations in Tat components that completely abolish export result in a marked induction of PspA protein synthesis, consistent with its proposed role in enhancing protein translocation via Tat.

scholarly journals A potential therapy for chordoma via antibody-dependent cell-mediated cytotoxicity employing NK or high-affinity NK cells in combination with cetuximab

2018 ◽  
Vol 128 (5) ◽  
pp. 1419-1427 ◽  
Author(s):  
Rika Fujii ◽  
Jeffrey Schlom ◽  
James W. Hodge
Keyword(s):  
Nk Cells ◽  
Nk Cell ◽  
Growth Factor Receptor ◽  
High Affinity ◽  
Dependent Cell ◽  
Epidermal Growth ◽  
First Time ◽  
Igg1 Isotype ◽  
Egfr Antibody

OBJECTIVEChordoma is a rare bone tumor derived from the notochord and is resistant to conventional therapies such as chemotherapy, radiotherapy, and targeting therapeutics. Expression of epidermal growth factor receptor (EGFR) in a large proportion of chordoma specimens indicates a potential target for therapeutic intervention. In this study the authors investigated the potential role of the anti-EGFR antibody cetuximab in immunotherapy for chordoma.METHODSSince cetuximab is a monoclonal antibody of the IgG1 isotype, it has the potential to mediate antibody-dependent cell-mediated cytotoxicity (ADCC) employing natural killer (NK) cells as effectors. Polymorphisms in the CD16 allele expressed on NK cells have been shown to influence the degree of ADCC of tumor cells, with the high-affinity valine (V)/V allele being responsible for more lysis than the V/phenylalanine (F) or FF allele. Unfortunately, however, only approximately 10% of the population expresses the VV allele on NK cells. An NK cell line, NK-92, has now been engineered to endogenously express IL-2 and the high-affinity CD16 allele. These irradiated high-affinity (ha)NK cells were analyzed for lysis of chordoma cells with and without cetuximab, and the levels of lysis observed in ADCC were compared with those of NK cells from donors expressing the VV, VF, and FF alleles.RESULTSHere the authors demonstrate for the first time 1) that cetuximab in combination with NK cells can mediate ADCC of chordoma cells; 2) the influence of the NK CD16 polymorphism in cetuximab-mediated ADCC for chordoma cell lysis; 3) that engineered haNK cells—that is, cells transduced to express the CD16 V158 FcγRIIIa receptor—bind cetuximab with similar affinity to normal NK cells expressing the high-affinity VV allele; and 4) that irradiated haNK cells induce ADCC with cetuximab in chordoma cells.CONCLUSIONSThese studies provide rationale for the use of cetuximab in combination with irradiated haNK cells for therapy for chordoma.

Identification of Streptomyces lividans proteins secreted by the twin-arginine translocation pathway following growth with different carbon sources

2008 ◽  
Vol 54 (7) ◽  
pp. 549-558 ◽  
Author(s):  
Julien Guimond ◽  
Rolf Morosoli
Keyword(s):  
Signal Sequence ◽  
Streptomyces Coelicolor ◽  
Carbon Sources ◽  
Streptomyces Lividans ◽  
Extracellular Proteins ◽  
Soil Extracts ◽  
Twin Arginine Translocation ◽  
Tat Pathway ◽  
Close Proximity ◽  
Dependent Protein

Genome-based signal peptide predictions classified Streptomyces coelicolor as the microorganism that secretes the most proteins through the twin-arginine translocation (Tat)-dependent secretion pathway. Availability of a ΔtatC mutant of the closely related strain Streptomyces lividans impaired Tat-dependent protein secretion and enabled identification of many extracellular proteins that are secreted via the Tat pathway. Proteomic techniques were applied to analyze proteins from the supernatants of log-phase cultures. Since the bacterial secretome depends mainly on the carbon sources available during growth, xylose, glucose, chitin, and soil extracts were used. A total of 63 proteins were identified, among which 7 were predicted by the TATscan program, and 20 were not predicted but contained a potential Tat signal motif. Thirteen proteins having no signal sequence could be co-transported by Tat-dependent proteins because the genes that encode these proteins are in close proximity in the genome. Finally, the presence of 23 proteins lacking signal peptides was difficult to explain. More secreted proteins could be identified as Tat substrates in varying carbon sources.

scholarly journals Antihuman immunoglobulin affinity immunoadsorption strongly decreases proteinuria in patients with relapsing nephrotic syndrome.

1998 ◽  
Vol 9 (9) ◽  
pp. 1709-1715
Author(s):  
J Dantal ◽  
Y Godfrin ◽  
R Koll ◽  
S Perretto ◽  
J Naulet ◽  
...  
Keyword(s):  
Nephrotic Syndrome ◽  
Ex Vivo ◽  
Protein A ◽  
Affinity Column ◽  
Focal Glomerulosclerosis ◽  
Direct Role ◽  
First Time ◽  
Firm Evidence

Approximately 20 to 30% of patients with idiopathic nephrotic syndrome and focal glomerulosclerosis experience a relapse of their nephrotic syndrome after transplantation. Previously, it has been shown that ex vivo immunoadsorption on protein A strongly (although transiently) reduces proteinuria in relapsing patients. To investigate whether the factor(s) that give rise to albuminuria are bound directly to protein A in the immunoadsorption procedure or are part of a complex with Ig, four patients with relapse of focal glomerulosclerosis presenting as nephrotic syndrome after transplantation were treated, sequentially, using a (non-protein A) anti-Ig affinity column and a protein A column. This study reports that the effect on proteinuria of immunoadsorption using an anti-Ig immunoaffinity column is comparable in its magnitude and kinetics to that of immunoadsorption on protein A. The two procedures were also equally effective in depleting the relapsing patients' plasma of a factor capable of altering the albumin permselectivity of isolated glomeruli in vitro. This study demonstrates for the first time that immunoglobulins have a role in the nephrotic syndrome. In addition, the fact that the two different immunoadsorption procedures both resulted in the removal of the same putative albuminuric factor in these patients and that no autoreactivity of eluted immunoglobulins was observed on human tissues strongly suggests that the factor or factors that may be responsible for immediate nephrotic syndrome after transplantation are bound to an immunoglobulin. However, no firm evidence can be yet provided against a direct role of immunoglobulins.

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 Role of OmpA in the Multidrug Resistance Phenotype of Acinetobacter baumannii

2013 ◽  
Vol 58 (3) ◽  
pp. 1806-1808 ◽  
Author(s):  
Younes Smani ◽  
Anna Fàbrega ◽  
Ignasi Roca ◽  
Viviana Sánchez-Encinales ◽  
Jordi Vila ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Acinetobacter Baumannii ◽  
Protein A ◽  
Multidrug Resistant ◽  
Nosocomial Pathogen ◽  
Content Type ◽  
Resistance Phenotype ◽  
Resistant Strains ◽  
First Time

ABSTRACTAcinetobacter baumanniihas emerged as a nosocomial pathogen with an increased prevalence of multidrug-resistant strains. The role of the outer membrane protein A (OmpA) in antimicrobial resistance remains poorly understood. In this report, disruption of theompAgene led to decreased MICs of chloramphenicol, aztreonam, and nalidixic acid. We have characterized, for the first time, the contribution of OmpA in the antimicrobial resistance phenotype ofA. baumannii.

scholarly journals Defining the DmsA Signal Sequence Interaction with DmsD And TatBC

2019 ◽  
Author(s):  
Deepanjan Ghosh ◽  
Sureshkumar Ramasamy
Keyword(s):  
Complex Formation ◽  
Signal Sequence ◽  
Factor Loading ◽  
Binding Studies ◽  
Redox Enzyme ◽  
Twin Arginine Translocation ◽  
Membrane Complex ◽  
Monomeric Complex ◽  
Tat Pathway ◽  
Complex Forms

AbstractRedox – enzyme maturation proteins (REMP) ensure co-factor loading and folding of proteins targeted to the twin-arginine translocation (Tat) pathway. The details of the interaction of a REMP with the corresponding signal sequence of its substrate are not well understood. Here, we demonstrate the features of the signal sequence for the Tat substrate DmsA (ssDmsA) responsible for complex formation with its REMP, DmsD, and with the Tat membrane complex TatB & TatC (TatBC). A heterologously expressed ssDmsA/DmsD complex forms two stochiometric populations corresponding to monomeric and dimeric forms of the complex. The monomeric complex has a higher affinity for the TatBC complex than the dimeric, which imply higher level regulation process to ensure the maturation of protein before translocation. Results from various binding studies yielded the shortest signal peptide required for ssDmsA/DmsA interaction and the region responsible for the TatBC interaction. Further experiments like alanine scanning in this peptide highlight the possible residues that are essential for this complex formation.

scholarly journals Cellular Function and Regulation of the Translationally Controlled Tumour Protein TCTP

2012 ◽  
Vol 5 (1) ◽  
pp. 19-32 ◽  
Author(s):  
Ulrich-Axel Bommer
Keyword(s):  
Cell Cycle ◽  
Current Knowledge ◽  
Protein A ◽  
Cloning And Sequencing ◽  
Functional Characterisation ◽  
Apoptotic Activity ◽  
First Time ◽  
Extracellular Activity ◽  
Translational Level

The ‘translationally controlled tumour protein’ TCTP was originally discovered 30 years ago by researchers interested in proteins regulated at the translational level. Cloning and sequencing confirmed the conservation of this protein among all eukaryotic kingdoms, but did not reveal any functional clue, and TCTP was listed in the databases as a ‘family’ of its own. The functional characterisation of this protein extended over more than a decade, leading to a plethora of individual functions and interactions that have been ascribed to this protein. A major addition to the functional characterisation of TCTP was the identification in 1995 of its histamine releasing factor (HRF) activity in allergic conditions, which for the first time described an extracellular activity for TCTP in human disease. This triggered a host of additional publications aimed at characterising this HRF activity, which are discussed in other articles of this issue. Another milestone in the elucidation of TCTP's function was the demonstration of its anti-apoptotic activity in 2001. Evidence is also accumulating for a role of TCTP in the cell cycle and in early development. This article provides an overview of the main cellular activities of TCTP. The second part will summarise our current knowledge on the mechanisms involved in regulating intracellular TCTP levels.

scholarly journals Novel Model To Study Virulence Determinants of Escherichia coli K1

2007 ◽  
Vol 75 (12) ◽  
pp. 5735-5739 ◽  
Author(s):  
Naveed Ahmed Khan ◽  
Graham John Goldsworthy
Keyword(s):  
Escherichia Coli ◽  
Protein A ◽  
Deletion Mutants ◽  
Virulence Determinants ◽  
E Coli ◽  
K 12 ◽  
Cytotoxic Necrotizing Factor 1 ◽  
First Time ◽  
The Brain

ABSTRACT It is shown here for the first time that locusts can be used as a model to study Escherichia coli K1 pathogenesis. E. coli K-12 strain HB101 has very low pathogenicity to locusts and does not invade the locust brain, whereas the injection of 2 × 106 E. coli K1 strain RS218 (O18:K1:H7) kills almost 100% of locusts within 72 h and invades the brain within 24 h of injection. Both mortality and invasion of the brain in locusts after injection of E. coli K1 require at least two of the known virulence determinants shown for mammals. Thus, deletion mutants that lack outer membrane protein A or cytotoxic necrotizing factor 1 have reduced abilities to kill locusts and to invade the locust brain compared to the parent E. coli K1. Interestingly, deletion mutants lacking FimH or the NeuDB gene cluster are still able to cause high mortality. It is argued that the likely existence of additional virulence determinants can be investigated in vivo by using this insect system.

Role of PKC isozymes in water transport in toad urinary bladder

1991 ◽  
Vol 49 ◽  
pp. 302-303
Author(s):  
A.J. Mia ◽  
L.X. Oakford ◽  
T. Yorio
Keyword(s):  
Urinary Bladder ◽  
Apical Membrane ◽  
Membrane Surface ◽  
Protein A ◽  
Cell Types ◽  
Leukemic Cells ◽  
Toad Urinary Bladder ◽  
Pkc Isozymes ◽  
Antibody Labeling

Protein kinase C (PKC) isozymes, when activated, are translocated to particulate membrane fractions for transport to the apical membrane surface in a variety of cell types. Evidence of PKC translocation was demonstrated in human megakaryoblastic leukemic cells, and in cardiac myocytes and fibroblasts, using FTTC immunofluorescent antibody labeling techniques. Recently, we reported immunogold localizations of PKC subtypes I and II in toad urinary bladder epithelia, following 60 min stimulation with Mezerein (MZ), a PKC activator, or antidiuretic hormone (ADH). Localization of isozyme subtypes I and n was carried out in separate grids using specific monoclonal antibodies with subsequent labeling with 20nm protein A-gold probes. Each PKC subtype was found to be distributed singularly and in discrete isolated patches in the cytosol as well as in the apical membrane domains. To determine if the PKC isozymes co-localized within the cell, a double immunogold labeling technique using single grids was utilized.

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