Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.108 (TAT)
 2,389 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to detect the protein delivery mediated by the PTD (protein transduction domain) of TAT Protein, a expression vector, named pT7460-GFP, was constructed by insert the PTD DNA Sequence, followed by a GFP (green fluorescent protein) gene fused in-frame, into the pT7450 vector. The TAT-GFP fusion protein was expressed in the E. coli ER2566. Most of the fusion protein was presented in the inclusion body. The protein was purified by Ni2+ affinity chromatography under denature conditions, then by a Sepharose Q column to remove urea. The soluble denatured protein was added directly to medium containing the Myeloma Cell SP2/0. It came out that the fusion protein could be detected delivered into the cells under fluorescent microscope in a short time.
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PMID:[The PTD domain of Tat protein enhance GFP protein delivering into myeloma cell SP2/0]. 1256 Dec 18

The SufI protein and the trimethylamine N-oxide reductase (TorA) are the two best-characterized prototype proteins exported by the Escherichia coli TAT system. Whereas SufI does not contain cofactors, TorA is a molybdo-enzyme and the acquisition of the molybdo-cofactor is a prerequisite for its translocation. The overproduction of each protein leads to the saturation of its translocation, but it was unknown if the overproduction of one substrate could saturate the TAT apparatus and block thus the translocation of other TAT substrates. Here, we showed that the overproduction of SufI saturated only its own translocation, but had no effect of the translocation of TorA and other TAT substrate analyzed. To dissect the saturation mechanism of TorA translocation, we shortened by about one-third of the TorA protein and removed nine consensus molybdo-cofactor-binding ligands. Like SufI, the truncated TorA (TorA502) did not contain cofactor and would not compete with the full length TorA for molybdo-cofactor acquisition. The overproduction of TorA502 completely inhibited the export of the full length TorA and dimethyl sulfoxide (DMSO) reductase, but had no effect on the translocation of SufI, nitrate-induced formate dehydrogenase and hydrogenase-2. Importantly, deletion of the twin-arginine signal peptide of TorA502 abolished the inhibitory effect. Moreover, the overproduction of the TorA signal peptide fused to the green fluorescence protein (GFP) was sufficient to block the TorA translocation. These results demonstrated that the twin-arginine signal peptide of the TorA protein specifically inhibits the translocation of a subset of TAT substrates, probably at the step of their targeting to the TAT apparatus.
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PMID:Specific inhibition of the translocation of a subset of Escherichia coli TAT substrates by the TorA signal peptide. 1263 52

We have tested the potential of EGFP, a derivative of the green fluorescent protein (GFP), as a passenger protein for the analysis of protein transport processes across the thylakoid membranes in chloroplasts. In contrast to the majority of fusion proteins commonly used in such studies, EGFP is not of plant origin and can therefore be assumed to behave like a "neutral" passenger protein that is unaffected by any internal plant regulatory circuits. Our in vitro transport experiments clearly demonstrate that EGFP is a suitable passenger protein that can be correctly targeted either to the stroma or to the thylakoid lumen if fused to the appropriate transit peptide. The transport of EGFP across the thylakoid membrane shows, however, a clear pathway preference. While the protein is efficiently targeted by the deltapH/TAT pathway, transport by the Sec pathway is barely detectable, either with isolated thylakoids or with intact chloroplasts. This pathway specificity suggests that EGFP is folded immediately after import into the chloroplast stroma, thus preventing further translocation across the thylakoid membrane by the Sec translocase. The data obtained provide a good basis for the development of molecular tools for transport studies using EGFP as a passenger protein. Furthermore, plant lines expressing corresponding EGFP chimeras are expected to allow in vivo studies on the transport and sorting mechanisms involved in the biogenesis of the chloroplast.
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PMID:Targeting of EGFP chimeras within chloroplasts. 1271 27

Protein transduction domains (PTDs) are short basic peptide sequences present in many cellular and viral proteins that mediate translocation across cellular membranes. PTDs have become widely used as tools for the delivery of high Mr polypeptides, polynucleotides, or nanoparticles to cells in culture; and even the transfer of cargo molecules to the tissue of live animals has been reported. These cell-permeable peptides are functional when fused in-frame to recombinant polypeptides or when chemically coupled to their cargo. The mechanism responsible for PTD-mediated membrane translocation is controversially discussed and may vary among the various PTDs reported in the literature. Thus direct physical interaction with membrane lipids resulting in vectorial delivery to cells has been proposed for the Antennapedia (Antp) PTD, whereas uptake by the retroviral TAT (transactivator of transcription) protein PTD seems to require cell surface-expressed glycosaminoglycans. The view that PTD-mediated cellular uptake is energy-independent has been dismissed recently as an artifact resulting from fixation of cells. The data reported here agree with and further extend this work. They support the idea that certain PTDs promote cellular uptake via endocytosis and require the expression of negatively charged glycosaminoglycans on the surface of the target cells. Uptake of Antp PTD conjugates or peptide-derivatized liposomes was blocked by heparan sulfate proteoglycans, whereas TAT-mediated uptake was inhibited by both heparin and dextran sulfate. Mutant cells defective for glycosaminoglycan synthesis showed dramatically reduced Antp- or TAT-mediated transmembrane transport confirming the role of these complex polysaccharides in PTD-mediated cellular uptake. The fact that PTDs selectively interact with distinct glycosaminoglycan species has implications for therapeutic applications and may allow targeting of selective tissues that differ in their surface-expressed glycosaminoglycan patterns.
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PMID:Antennapedia and HIV transactivator of transcription (TAT) "protein transduction domains" promote endocytosis of high molecular weight cargo upon binding to cell surface glycosaminoglycans. 1283 62

Protein transduction domains (PTD), such as the HIV TAT and the herpes simplex virus VP22 proteins, are reported to translocate across the membranes of mammalian cells. The mechanism of PTD membrane translocation has largely remained elusive, but recent studies suggest that the reported PTD translocation is due to a fixation artifact. We have constructed and expressed the PTDs VP22, TAT, polyarginine, and polylysine fused to the green fluorescent protein to visualize these proteins in both living and fixed cells. The investigated PTDs strongly adhered to the surface of living cells and were internalized by constitutive endocytosis. No cytosolic or nuclear import of the proteins was detected. In contrast, the PTD-GFP fusion proteins were redistributed to the cytosol and nucleus directly after fixation. Our findings suggest that the PTDs only mediate cell surface adherence, a property shared with many other positively charged macromolecules. The cell surface adherence results in endocytosis and accumulation of proteins in endosomes. We suggest that the biological effects observed for PTD fusion proteins are due to cell surface interactions and internalization of the proteins into cells by classical endocytosis.
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PMID:Cell surface adherence and endocytosis of protein transduction domains. 1284 37

HIV-1-based vectors are promising tools for gene therapy because of their ability to integrate into nondividing cells. Their safety in clinical applications remains a major concern. Recombination events occurring among plasmid constructs during vector production could potentially lead to the generation of replication-competent viruses. The safety of HIV-1-based vectors can be improved by removing all regions of the viral genome that are not absolutely required for vector production or function. In this study, we demonstrate that the HIV-1 rev gene is dispensable for the production of HIV-1-based vectors if the vector-producing cells are supplied with purified Rev protein. We compared the efficiency of vector production among Rev, TAT-Rev (Rev fused to the protein transduction domain of the HIV TAT protein), and Rev/Pep-1 (Rev complexed with the carrier peptide Pep-1). Our results showed that 293T cells efficiently internalized TAT-Rev and Rev/Pep-1 and high-titer vector preparations were obtained with this approach. Vectors generated by such an approach showed little difference in their efficiencies of transduction of established cell lines and primary cells compared with vectors generated by standard plasmid cotransfection. Eliminating the requirement for the HIV-1 rev gene during vector production should improve the safety of applying HIV vectors in human clinical trials.
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PMID:HIV vector production mediated by Rev protein transduction. 1290 55

We have reported previously that HIV-TAT-dominant negative (dn) Ras inhibits eosinophil adhesion to ICAM-1 after activation by IL-5 and eotaxin. In this study, we evaluated the role of Ras in Ag-induced airway inflammation and hyperresponsiveness by i.p. administration into mice of dnRas, which was fused to an HIV-TAT protein transduction domain (TAT-dnRas). Uptake of TAT-dnRas (t(1/2) = 12 h) was demonstrated in leukocytes after i.p. administration. OVA-sensitization significantly increased eosinophil and lymphocyte numbers in bronchoalveolar lavage fluid 24 h after final challenge. Treatment of animals with 3-10 mg/kg TAT-dnRas blocked the migration of eosinophils from 464 +/- 91 x 10(3)/ml to 288 +/- 79 x 10(3)/ml with 3 mg/kg of TAT-dnRas (p < 0.05), and further decreased to 116 +/- 63 x 10(3)/ml after 10 mg/kg TAT-dnRas (p < 0.01). Histological examination demonstrated that inflammatory cell infiltration (largely eosinophils and mononuclear cells) and mucin production around the airways caused by OVA were blocked by TAT-dnRas. OVA challenge also caused airway hyperresponsiveness to methacholine, which was dose dependently blocked by treatment with TAT-dnRas. TAT-dnRas also blocked Ag-induced IL-4 and IL-5, but not IFN-gamma, production in lung tissue. Intranasal administration of IL-5 caused eosinophil migration into the airway lumen, which was attenuated by pretreatment with TAT-dnRas. By contrast, TAT-green fluorescent protein or dnRas lacking the TAT protein transduction domain did not block airway inflammation, cytokine production, or airway hyperresponsiveness. We conclude that Ras mediates Th2 cytokine production, airway inflammation, and airway hyperresponsiveness in immune-sensitized mice.
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PMID:Blockade of airway inflammation and hyperresponsiveness by HIV-TAT-dominant negative Ras. 1453 Mar 63

Activation of group IV cytosolic phospholipase A(2) (gIV-PLA(2)) is the essential first step in the synthesis of inflammatory eicosanoids and in integrin-mediated adhesion of leukocytes. Prior investigations have demonstrated that phosphorylation of gIV-PLA(2) results from activation of at least two isoforms of mitogen-activated protein kinase (MAPK). We investigated the potential role of phosphoinositide 3-kinase (PI3K) in the activation of gIV-PLA(2) and the hydrolysis of membrane phosphatidylcholine in fMLP-stimulated human blood eosinophils. Transduction into eosinophils of Deltap85, a dominant negative form of class IA PI3K adaptor subunit, fused to an HIV-TAT protein transduction domain (TAT-Deltap85) concentration dependently inhibited fMLP-stimulated phosphorylation of protein kinase B, a downstream target of PI3K. FMLP caused increased arachidonic acid (AA) release and secretion of leukotriene C(4) (LTC(4)). TAT-Deltap85 and LY294002, a PI3K inhibitor, blocked the phosphorylation of gIV-PLA(2) at Ser(505) caused by fMLP, thus inhibiting gIV-PLA(2) hydrolysis and production of AA and LTC(4) in eosinophils. FMLP also caused extracellular signal-related kinases 1 and 2 and p38 MAPK phosphorylation in eosinophils; however, neither phosphorylation of extracellular signal-related kinases 1 and 2 nor p38 was inhibited by TAT-Deltap85 or LY294002. Inhibition of 1) p70 S6 kinase by rapamycin, 2) protein kinase B by Akt inhibitor, or 3) protein kinase C by Ro-31-8220, the potential downstream targets of PI3K for activation of gIV-PLA(2), had no effect on AA release or LTC(4) secretion caused by fMLP. We find that PI3K is required for gIV-PLA(2) activation and hydrolytic production of AA in activated eosinophils. Our data suggest that this essential PI3K independently activates gIV-PLA(2) through a pathway that does not involve MAPK.
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PMID:Activation of group IV cytosolic phospholipase A2 in human eosinophils by phosphoinositide 3-kinase through a mitogen-activated protein kinase-independent pathway. 1453 Mar 66

Internalization of antibodies into mammalian cells is a useful method for analyzing and regulating cellular function. In this study, we developed a novel method for the delivery of antibodies into cells using the TAT-fused protein. This fusion protein consists of two functional domains, the protein transduction domain of HIV-1 TAT and the B domain of staphylococcal protein A (SpA), which has an ability to bind to the IgG. The TAT-SpA fusion protein was mixed with fluorescence-labeled rabbit IgG and added to cells. The internalization of antibody was analyzed using confocal microscopy and flow cytometry in living cells. As a result, fluorescence-labeled IgG with the TAT-SpA fusion protein was observed intracellularly. Flow cytometry results demonstrated time course and dose dependence relationships of antibody internalization. These results suggest that the TAT-SpA fusion protein can be a useful reagent for the delivery of antibody into cells.
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PMID:Intracellular delivery of antibodies using TAT fusion protein A. 1455 Feb 63

Phosphoinositide 3-kinase (PI3K) is thought to contribute to the pathogenesis of asthma by effecting the recruitment, activation, and apoptosis of inflammatory cells. We examined the role of class IA PI3K in antigen-induced airway inflammation and hyperresponsiveness by i.p. administration into mice of Deltap85 protein, a dominant negative form of the class IA PI3K regulatory subunit, p85alpha, which was fused to HIV-TAT (TAT-Deltap85). Intraperitoneal administration of TAT-Deltap85 caused time-dependent transduction into blood leukocytes, and inhibited activated phosphorylation of protein kinase B (PKB), a downstream target of PI3K, in lung tissues in mice receiving intranasal FMLP. Antigen challenge elicited pulmonary infiltration of lymphocytes, eosinophils and neutrophils, increase in mucus-containing epithelial cells, and airway hyperresponsiveness to methacholine. Except for modest airway neutrophilia, these effects all were blocked by treatment with 3-10 mg/kg of TAT-Deltap85. There was also significant reduction in IL-5 and IL-4 secretion into the BAL. Intranasal administration of IL-5 caused eosinophil migration into the airway lumen, which was attenuated by systemic pretreatment with TAT-Deltap85. We conclude that PI3K has a regulatory role in Th2-cell cytokine secretion, airway inflammation, and airway hyperresponsiveness in mice.
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PMID:Blockade of inflammation and airway hyperresponsiveness in immune-sensitized mice by dominant-negative phosphoinositide 3-kinase-TAT. 1462 11


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