Translocation of the cell-penetrating Tat peptide across artificial bilayers and into living cells.

2005 ◽  
Vol 72 ◽  
pp. 199-209 ◽  
Author(s):  
Paul Curnow ◽  
Harry Mellor ◽  
David J. Stephens ◽  
Mark Lorch ◽  
Paula J. Booth
Keyword(s):  
Catalytic Domain ◽  
Cysteine Residue ◽  
Live Cells ◽  
Tat Protein ◽  
Tat Peptide ◽  
Fluorescence Confocal Microscopy ◽  
Activating Transcription Factor ◽  
Artificial Bilayers ◽  
Hiv 1

The ability of a short, charged peptide to penetrate synthetic DOPC (1,2-dioleoyl-sn-3-glycerophosphocholine) liposomes was investigated by fluorescence confocal microscopy. The peptide, termed Tat (trans-activating transcription factor), was a 14-mer derived from the region of the HIV-1 Tat protein responsible for cellular internalization. This Tat peptide was labelled at a C-terminal cysteine residue with the fluorescent probes IAF (5-iodoacetamidofluorescein) or A568 (Alexa Fluor 568). The Tat-IAF conjugate was directly observed entering liposomes at room temperature (approx. 258C) in the absence of pH gradient, ATP or other energy source. The uptake of the Tat-A568 conjugate in unfixed, live HeLa cells was found to be via endocytosis, as expected. In contrast, when the peptide was attached to an IAF-labelled 25 kDa protein corresponding to the catalytic domain of Clostridium botulinum C3 exotoxin, this larger, Tat-C3-IAF construct was not able to enter liposomes, although it localized similarly to Tat-A568 in live cells. The data suggest that Tat peptide can cross synthetic bilayers spontaneously in vitro, but that size and type of cargo may limit this behaviour.

scholarly journals Functional Differences between Human and Bovine Immunodeficiency Virus Tat Transcription Factors

2000 ◽  
Vol 74 (10) ◽  
pp. 4666-4671 ◽  
Author(s):  
Hal P. Bogerd ◽  
Heather L. Wiegand ◽  
Paul D. Bieniasz ◽  
Bryan R. Cullen
Keyword(s):  
Cooperative Interaction ◽  
Bovine Immunodeficiency Virus ◽  
Viral Gene ◽  
Tat Protein ◽  
Cyclin T1 ◽  
Immunodeficiency Virus ◽  
Cellular Cofactor ◽  
Ltr Promoter ◽  
Hiv 1

ABSTRACT Transcriptional transactivation of the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) promoter element by the essential viral Tat protein requires recruitment of positive transcription elongation factor b (P-TEFb) to the viral TAR RNA target. The recruitment of P-TEFb, which has been proposed to be necessary and sufficient for activation of viral gene expression, is mediated by the highly cooperative interaction of Tat and cyclin T1, an essential component of P-TEFb, with the HIV-1 TAR element. Species, such as rodents, that encode cyclin T1 variants that are unable to support TAR binding by the Tat-cyclin T1 heterodimer are also unable to support HIV-1 Tat function. In contrast, we here demonstrate that the bovine immunodeficiency virus (BIV) Tat protein is fully able to bind to BIV TAR both in vivo and in vitro in the absence of any cellular cofactor. Nevertheless, BIV Tat can specifically recruit cyclin T1 to the BIV TAR element, and this recruitment is as essential for BIV Tat function as it is for HIV-1 Tat activity. However, because the cyclin T1 protein does not contribute to TAR binding, BIV Tat is able to function effectively in cells from several species that do not support HIV-1 Tat function. Thus, BIV Tat, while apparently dependent on the same cellular cofactor as the Tat proteins encoded by other lentiviruses, is nevertheless unique in terms of the mechanism used to recruit the BIV Tat-cyclin T1 complex to the viral LTR promoter.

The HIV-1 Tat Protein Stimulates Reverse Transcription In Vitro

2007 ◽  
Vol 5 (5) ◽  
pp. 474-483 ◽  
Author(s):  
Ann Apolloni ◽  
Luke Meredith ◽  
Andreas Suhrbier ◽  
Rosemary Kiernan ◽  
David Harrich
Keyword(s):  
Reverse Transcription ◽  
Tat Protein ◽  
Transcription In Vitro ◽  
Hiv 1

scholarly journals Domains in the SPT5 Protein That Modulate Its Transcriptional Regulatory Properties

2000 ◽  
Vol 20 (9) ◽  
pp. 2970-2983 ◽  
Author(s):  
Dmitri Ivanov ◽  
Youn Tae Kwak ◽  
Jun Guo ◽  
Richard B. Gaynor
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcriptional Repression ◽  
Transcriptional Elongation ◽  
Tat Protein ◽  
C Terminus ◽  
Heptad Repeats ◽  
And Function ◽  
Hiv 1

ABSTRACT SPT5 and its binding partner SPT4 regulate transcriptional elongation by RNA polymerase II. SPT4 and SPT5 are involved in both 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB)-mediated transcriptional inhibition and the activation of transcriptional elongation by the human immunodeficiency virus type 1 (HIV-1) Tat protein. Recent data suggest that P-TEFb, which is composed of CDK9 and cyclin T1, is also critical in regulating transcriptional elongation by SPT4 and SPT5. In this study, we analyze the domains of SPT5 that regulate transcriptional elongation in the presence of either DRB or the HIV-1 Tat protein. We demonstrate that SPT5 domains that bind SPT4 and RNA polymerase II, in addition to a region in the C terminus of SPT5 that contains multiple heptad repeats and is designated CTR1, are critical for in vitro transcriptional repression by DRB and activation by the Tat protein. Furthermore, the SPT5 CTR1 domain is a substrate for P-TEFb phosphorylation. These results suggest that C-terminal repeats in SPT5, like those in the RNA polymerase II C-terminal domain, are sites for P-TEFb phosphorylation and function in modulating its transcriptional elongation properties.

Acetylation of the HIV-1 Tat protein: an in vitro study

2003 ◽  
Vol 376 (7) ◽  
pp. 994-1005 ◽  
Author(s):  
Wilma Dormeyer ◽  
Alexander Dorr ◽  
Melanie Ott ◽  
Martina Schn�lzer
Keyword(s):  
In Vitro Study ◽  
Vitro Study ◽  
Tat Protein ◽  
Hiv 1

Effect of Antibody to HIV-1 Tat Protein on Viral Replication in Vitro and Progression of HIV-1 Disease in Vivo

1995 ◽  
Vol 10 (4) ◽  
pp. 408-416 ◽  
Author(s):  
M C Re ◽  
G Furlini ◽  
M Vignoli ◽  
E Ramazzotti ◽  
G Roderigo ◽  
...  
Keyword(s):  
Viral Replication ◽  
Tat Protein ◽  
Hiv 1

scholarly journals In vitro nuclear interactome of the HIV-1 Tat protein

Retrovirology ◽  
2009 ◽  
Vol 6 (S2) ◽  
Author(s):  
Virginie W Gautier ◽  
Lili Gu ◽  
Niaobh O'Donoghue ◽  
Stephen Pennington ◽  
Noreen Sheehy ◽  
...  
Keyword(s):  
Tat Protein ◽  
Hiv 1

scholarly journals Peptides Derived from the Reverse Transcriptase of Human Immunodeficiency Virus Type 1 as Novel Inhibitors of the Viral Integrase

2005 ◽  
Vol 280 (23) ◽  
pp. 21987-21996 ◽  
Author(s):  
Iris Oz Gleenberg ◽  
Orna Avidan ◽  
Yehuda Goldgur ◽  
Alon Herschhorn ◽  
Amnon Hizi
Keyword(s):  
Reverse Transcriptase ◽  
Catalytic Domain ◽  
Three Dimensional ◽  
Specific Protein ◽  
Strand Transfer ◽  
Catalytic Core ◽  
Core Domain ◽  
Inhibitory Peptides ◽  
Hiv 1

Recent studies have shown that the integrase (IN) of HIV-1 is inhibited in vitro by HIV-1 reverse transcriptase (RT). We further investigated the specific protein sequences of RT that were involved in this inhibition by screening a complete library of RT-derived peptides for their inhibition of IN activities. Two 20-residue peptides, peptide 4286, derived from the RT DNA polymerase domain, and the one designated 4321, from the RT ribonuclease H domain, inhibit the enzymatic activities of IN in vitro. The former peptide inhibits all three IN-associated activities (3′-end processing, strand transfer, and disintegration), whereas the latter one inhibits primarily the first two functions. We showed the importance of the sequences and peptide length for the effective inhibition of IN activities. Binding assays of the peptides to IN (with no DNA substrate present) indicated that the two inhibitory peptides (as well as several non-inhibitory peptides) interact directly with IN. Moreover, the isolated catalytic core domain of IN also interacted directly with the two inhibitory peptides. Nevertheless, only peptide 4286 can inhibit the disintegration activity associated with the IN core domain, because this activity is the only one exhibited by this domain. This result was expected from the lack of inhibition of disintegration of full-length IN by peptide 4321. The data and the three-dimensional models presented suggested that the inhibition resulted from steric hindrance of the catalytic domain of IN. This information can substantially facilitate the development of novel drugs against HIV INs and thus contribute to the fight against AIDS.

scholarly journals Fibroblast Growth Factor-2 and the HIV-1 Tat Protein Synergize in Promoting Bcl-2 Expression and Preventing Endothelial Cell Apoptosis: Implications for the Pathogenesis of AIDS-Associated Kaposi's Sarcoma

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Cecilia Sgadari ◽  
Giovanni Barillari ◽  
Clelia Palladino ◽  
Stefania Bellino ◽  
Brunella Taddeo ◽  
...  
Keyword(s):  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Vascular Tumor ◽  
Fibroblast Growth ◽  
Tat Protein ◽  
Immunodeficiency Virus ◽  
Hiv 1

Kaposi's sarcoma (KS) is a vascular tumor frequently occurring in Human Immunodeficiency Virus- (HIV-) 1-infected individuals. Our previous work indicated that the angiogenic fibroblast growth factor (FGF)-2 and the Tat protein of HIV-1, both expressed in KS lesions of HIV-infected patients, synergize at inducing angioproliferative, KS-like lesions in mice. Here we show that the development of angioproliferative lesions promoted in mice by combined Tat and FGF-2 associates with an increase in the levels of expression of the antiapoptotic Bcl-2 protein. Upregulation of Bcl-2 expression by combined FGF-2 and Tat occurs alsoin vitro, and this protects human primary endothelial cells from programmed cell death. As Bcl-2 is expressed in human KS lesions in a fashion paralleling the progression of the disease, these findings suggest a molecular mechanism by which Tat and FGF-2 cooperate in KS maintenance and progression in HIV-infected individuals.

scholarly journals In vitro nuclear interactome of the HIV-1 Tat protein

Retrovirology ◽  
2009 ◽  
Vol 6 (1) ◽  
Author(s):  
Virginie W Gautier ◽  
Lili Gu ◽  
Niaobh O'Donoghue ◽  
Stephen Pennington ◽  
Noreen Sheehy ◽  
...  
Keyword(s):  
Tat Protein ◽  
Hiv 1
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