scholarly journals Interaction of DevR with Multiple Binding Sites Synergistically Activates Divergent Transcription of narK2-Rv1738 Genes in Mycobacterium tuberculosis

2008 ◽  
Vol 190 (15) ◽  
pp. 5394-5403 ◽  
Author(s):  
Santosh Chauhan ◽  
Jaya Sivaswami Tyagi
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Binding Sites ◽  
Fluorescent Protein ◽  
Mutational Analysis ◽  
Hypoxic Conditions ◽  
Multiple Binding Sites ◽  
Low Concentrations ◽  
Intergenic Sequences ◽  
Reporter Assays ◽  
Green Fluorescent

ABSTRACT Under hypoxic conditions or upon exposure to low concentrations of nitric oxide, DevR transcriptional regulator mediates the activation of ∼50 genes that are believed to assist in dormancy development in Mycobacterium tuberculosis. Most of the strongly induced genes are characterized by the presence of one to four copies of a Dev box-like sequence at an upstream location. Among these are several gene pairs that are transcribed in opposite directions. This arrangement could provide for coordinated control of the adjacent genes under inducing conditions. In this work, we report the first detailed analysis of DevR-mediated hypoxic regulation of narK2-Rv1738 genes that are oppositely oriented in M. tuberculosis. Phosphorylated DevR interacts with intergenic sequences and protects ∼80 bp of DNA that contains three binding sites, designated Dev boxes D1, D2, and D3. The hypoxia-specific transcription start points of narK2 and Rv1738 were mapped, and it was noted that the −35 elements of both promoters overlapped with the proximally placed Dev box. DevR bound cooperatively to adjacently placed D2 and D3 boxes while binding to D1 was independent of DevR interaction with the D2 and D3 boxes. Mutational analysis and green fluorescent protein reporter assays established that the three Dev boxes function synergistically to mediate maximal transcriptional induction of both narK2 and Rv1738 in hypoxic cultures of M. tuberculosis. Analysis of narK2 promoter activity indicates that it is under negative regulation in addition to DevR-mediated positive regulation and also reveals differences between M. tuberculosis and Mycobacterium bovis BCG.

scholarly journals Functional Characterization of Candida albicans ABC Transporter Cdr1p

2003 ◽  
Vol 2 (6) ◽  
pp. 1361-1375 ◽  
Author(s):  
Suneet Shukla ◽  
Preeti Saini ◽  
Smriti ◽  
Sudhakar Jha ◽  
Suresh V. Ambudkar ◽  
...  
Keyword(s):  
Binding Sites ◽  
Fluorescent Protein ◽  
Mutational Analysis ◽  
Substrate Binding ◽  
Functional Characterization ◽  
Drug Binding ◽  
Transmembrane Segment ◽  
Green Fluorescent ◽  
Substrate Binding Sites ◽  
First Time

ABSTRACT In view of the importance of Candida drug resistance protein (Cdr1p) in azole resistance, we have characterized it by overexpressing it as a green fluorescent protein (GFP)-tagged fusion protein (Cdr1p-GFP). The overexpressed Cdr1p-GFP in Saccharomyces cerevisiae is shown to be specifically labeled with the photoaffinity analogs iodoarylazidoprazosin (IAAP) and azidopine, which have been used to characterize the drug-binding sites on mammalian drug-transporting P-glycoproteins. While nystatin could compete for the binding of IAAP, miconazole specifically competed for azidopine binding, suggesting that IAAP and azidopine bind to separate sites on Cdr1p. Cdr1p was subjected to site-directed mutational analysis. Among many mutant variants of Cdr1p, the phenotypes of F774A and ΔF774 were particularly interesting. The analysis of GFP-tagged mutant variants of Cdr1p revealed that a conserved F774, in predicted transmembrane segment 6, when changed to alanine showed increased binding of both photoaffinity analogues, while its deletion (ΔF774), as revealed by confocal microscopic analyses, led to mislocalization of the protein. The mislocalized ΔF774 mutant Cdr1p could be rescued to the plasma membrane as a functional transporter by growth in the presence of a Cdr1p substrate, cycloheximide. Our data for the first time show that the drug substrate-binding sites of Cdr1p exhibit striking similarities with those of mammalian drug-transporting P-glycoproteins and despite differences in topological organization, the transmembrane segment 6 in Cdr1p is also a major contributor to drug substrate-binding site(s).

scholarly journals Development of an Intracellular Screen for New Compounds Able To Inhibit Mycobacterium tuberculosis Growth in Human Macrophages

2015 ◽  
Vol 60 (1) ◽  
pp. 640-645 ◽  
Author(s):  
Flavia Sorrentino ◽  
Ruben Gonzalez del Rio ◽  
Xingji Zheng ◽  
Jesus Presa Matilla ◽  
Pedro Torres Gomez ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
High Throughput Screening ◽  
Fluorescent Protein ◽  
Screening Assay ◽  
Human Macrophages ◽  
High Throughput Screening Assay ◽  
Primary Identification ◽  
Green Fluorescent ◽  
Development And Validation ◽  
New Compounds

ABSTRACTHere we describe the development and validation of an intracellular high-throughput screening assay for finding new antituberculosis compounds active in human macrophages. The assay consists of a luciferase-based primary identification assay, followed by a green fluorescent protein-based secondary profiling assay. Standard tuberculosis drugs and 158 previously recognized active antimycobacterial compounds were used to evaluate assay robustness. Data show that the assay developed is a short and valuable tool for the discovery of new antimycobacterial compounds.

Initiation and maturation of I-Z-I bodies in the growth tips of transfected myotubes

1999 ◽  
Vol 112 (22) ◽  
pp. 4101-4112 ◽  
Author(s):  
K. Ojima ◽  
Z.X. Lin ◽  
Z.Q. Zhang ◽  
T. Hijikata ◽  
S. Holtzer ◽  
...  
Keyword(s):  
Binding Sites ◽  
Thin Filament ◽  
Fluorescent Protein ◽  
De Novo ◽  
Actin Binding ◽  
Double Staining ◽  
Green Fluorescent ◽  
Short Time ◽  
Alpha Actin ◽  
De Novo Assembling

While over a dozen I-Z-I proteins are expressed in postmitotic myoblasts and myotubes it is unclear how, when, or where these first assemble into transitory I-Z-I bodies (thin filament/Z-band precursors) and, a short time later, into definitive I-Z-I bands. By double-staining the growth tips of transfected myotubes expressing (a) MYC-tagged s-alpha-actinins (MYC/s-alpha-actinins) or (b) green fluorescent protein-tagged titin cap (GFP/T-cap) with antibodies against MYC and I-Z-I band proteins, we found that the de novo assembly of I-Z-I bodies and their maturation into I-Z-I bands involved relatively concurrent, cooperative binding and reconfiguration of, at a minimum, 5 integral Z-band molecules. These included s-alpha-actinin, nebulin, titin, T-cap and alpha-actin. Resolution of the approximately 1.0 microm polarized alpha-actin/nebulin/tropomyosin/troponin thin filament complexes occurred subsequent to the maturation of Z-bands into a dense tetragonal configuration. Of particular interest is finding that mutant MYC/s-alpha-actinin peptides (a) lacking spectrin-like repeats 1–4, or consisting of spectrin-like repeats 1–4 only, as well as (b) mutants/fragments lacking titin or alpha-actin binding sites, were promptly and exclusively incorporated into de novo assembling I-Z-I bodies and definitive I-Z-I bands as was exogenous full length MYC/s-alpha-actinin or GFP/T-cap.

scholarly journals The Mycobacterium tuberculosis Phagosome in Human Macrophages Is Isolated from the Host Cell Cytoplasm

2002 ◽  
Vol 70 (10) ◽  
pp. 5800-5807 ◽  
Author(s):  
Daniel L. Clemens ◽  
Bai-Yu Lee ◽  
Marcus A. Horwitz
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Host Cell ◽  
Fluorescent Protein ◽  
Medium Size ◽  
Immunogold Electron Microscopy ◽  
Human Macrophages ◽  
Fab Fragments ◽  
Green Fluorescent ◽  
Major Surface ◽  
Phagosomal Membrane

ABSTRACT Knowledge of whether Mycobacterium tuberculosis resides within a relatively impermeable membrane-bound vacuole or is free within the cytoplasm within its host cell is central to an understanding of the immunobiology of this intracellular parasite but is a matter of controversy. To explore this issue, we assessed the accessibility of medium-size protein molecules (Fab fragments of 50,000 Da) to M. tuberculosis within human macrophages. We infected the macrophages with wild-type or green fluorescent protein-expressing M. tuberculosis, microinjected Fab fragments directed against a major surface antigen of M. tuberculosis into the host cell, and assayed the accessibility of the bacteria to the Fab fragments by both immunofluorescence microscopy and immunogold electron microscopy. Whereas microinjected intact immunoglobulin G molecules against cytoplasmic early endosomal antigen 1 readily stained this antigen, microinjected Fab fragments against M. tuberculosis did not stain the bacterium within its phagosome. In contrast, microinjected Fab fragments against Listeria monocytogenes, an intracellular bacterium known to permeabilize its phagosomal membrane, strongly stained this bacterium. Our study shows that M. tuberculosis resides in an isolated phagosome that is relatively impermeable to cytoplasmic constituents.

scholarly journals Enhanced Survival of Salmonella enterica in Vesicles Released by a Soilborne Tetrahymena Species

2005 ◽  
Vol 71 (3) ◽  
pp. 1562-1569 ◽  
Author(s):  
M. T. Brandl ◽  
B. M. Rosenthal ◽  
A. F. Haxo ◽  
S. G. Berk
Keyword(s):  
Public Health ◽  
Salmonella Enterica ◽  
Fluorescent Protein ◽  
Survival Rates ◽  
Human Pathogen ◽  
Initial Ratio ◽  
Calcium Hypochlorite ◽  
Human Macrophages ◽  
Low Concentrations ◽  
Green Fluorescent

ABSTRACT Nondestructive ingestion by soilborne protozoa may enhance the environmental resiliency of important bacterial pathogens and may model how such bacteria evade destruction in human macrophages. Here, the interaction of Salmonella enterica serovar Thompson with a soilborne Tetrahymena sp. isolate was examined using serovar Thompson cells labeled with the green fluorescent protein. The bacteria were mixed in solution with cells of Tetrahymena at several ratios. During incubation with serovar Thompson, Tetrahymena cells released a large number of vesicles containing green fluorescent serovar Thompson cells. In comparison, grazing on Listeria monocytogenes cells resulted in their digestion and thus the infrequent release of this pathogen in vesicles. The number of serovar Thompson cells per vesicle increased significantly as the initial ratio of serovar Thompson to Tetrahymena cells increased from 500:1 to 5,000:1. The density of serovar Thompson was as high as 50 cells per vesicle. Staining with propidium iodide revealed that a significantly higher proportion of serovar Thompson cells remained viable when enclosed in vesicles than when free in solution. Enhanced survival rates were observed in vesicles that were secreted by both starved (F = 28.3, P < 0.001) and unstarved (F = 14.09, P < 0.005) Tetrahymena cells. Sequestration in vesicles also provided greater protection from low concentrations of calcium hypochlorite. Thus, the release of this human pathogen from Tetrahymena cells in high-density clusters enclosed in a membrane may have important implications for public health.

scholarly journals abc3 + Encodes an Iron-Regulated Vacuolar ABC-Type Transporter in Schizosaccharomyces pombe

2009 ◽  
Vol 9 (1) ◽  
pp. 59-73 ◽  
Author(s):  
Benoît Pouliot ◽  
Mehdi Jbel ◽  
Alexandre Mercier ◽  
Simon Labbé
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Chromatin Immunoprecipitation ◽  
Transcriptional Activity ◽  
Fluorescent Protein ◽  
Dependent Manner ◽  
Ferric Reductase ◽  
Low Concentrations ◽  
Green Fluorescent ◽  
A Site

ABSTRACT Studies have shown the fundamental contribution of the yeast vacuole as a site for storage and detoxification of metals. Whereas the transmembrane proteins responsible for iron transport into and out of the vacuole have been identified in Saccharomyces cerevisiae, less information is available concerning the mobilization of vacuolar iron stores in Schizosaccharomyces pombe. In this study, we report the identification of a gene designated abc3 + that encodes a protein which exhibits sequence homology with the ABCC subfamily of ATP-binding cassette transporters. The transcription of abc3 + is induced by low concentrations of iron but repressed by high levels of iron. The iron-mediated repression of abc3 + required a functional fep1 + gene. Chromatin immunoprecipitation assays showed that Fep1 associates with the abc3 + promoter in vivo, in an iron-dependent manner. Microscopic analyses revealed that a functional Abc3-green fluorescent protein localizes to the membrane vacuole when iron levels were low. Abc3 was required for growth in low-iron medium in the absence of the transport system mediated by Fio1 and Fip1. abc3Δ cells exhibited increased levels of expression of the frp1 + -encoded ferric reductase, suggesting a loss of Fep1 repression and, consequently, the activation of Fep1-regulated genes. When abc3 + was expressed using the nmt1 + promoter system, its induction led to a reduced transcriptional activity of the frp1 + gene. Because S. pombe does not possess vacuolar membrane-localized orthologs to S. cerevisiae Fth1, Fet5, and Smf3, our findings suggested that Abc3 may be responsible for mobilizing stored iron from the vacuole to the cytosol in response to iron deficiency.

scholarly journals In VitroReporter Assays for Screening of Chemicals That Disrupt Androgen Signaling

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Gargi Bagchi Bhattacharjee ◽  
S. M. Paul Khurana
Keyword(s):  
Fluorescent Protein ◽  
Cell Systems ◽  
Reporter Assays ◽  
Increased Sensitivity ◽  
Global Concern ◽  
Green Fluorescent ◽  
Male Hormones ◽  
Developmental Windows ◽  
Antiandrogenic Activity

Endocrine disruptive chemicals (EDCs) modulate hormone signaling and cause developmental and reproductive anomalies. Today, there is a global concern regarding endocrine disruption effects, particularly those mediated by the androgen receptor (AR). Androgen or male hormones are critical for the development and maintenance of male characteristics and numerous EDCs exist in the environment with the potential to disrupt androgen action. The threat is more during critical developmental windows when there is increased sensitivity to these compounds. Timely screening and detection of the EDCs is essential to minimize deleterious effects produced by these toxic chemicals. As a first line of screening,in vitrotranscription assays are very useful due to their speed, convenience, and cost effectiveness. In this paper, recentin vitroreporter assays for detecting androgenic or antiandrogenic activity of EDCs have been reviewed. Two important cell systems used for this purpose, namely, the mammalian or yeast cell systems, have been discussed. Use of reporter genes such as bacterial luciferase (lux) and green fluorescent protein (gfp) has significantly improved speed and sensitivity of detection. Also, many of the current reporter assay systems can be used in a high throughput format allowing speedy evaluation of multiple potential EDCs at a lower price.

scholarly journals Matrix protein of Vesicular stomatitis virus harbours a cryptic mitochondrial-targeting motif

2006 ◽  
Vol 87 (11) ◽  
pp. 3379-3384 ◽  
Author(s):  
Brian D. Lichty ◽  
Heidi McBride ◽  
Stephen Hanson ◽  
John C. Bell
Keyword(s):  
Vesicular Stomatitis Virus ◽  
Matrix Protein ◽  
Fluorescent Protein ◽  
Mutational Analysis ◽  
M Protein ◽  
Mitochondrial Targeting ◽  
M Gene ◽  
The Matrix ◽  
Vesicular Stomatitis ◽  
Green Fluorescent

Vesicular stomatitis virus (VSV) is a rhabdovirus that has attracted attention of late as an oncolytic virus and as a vaccine vector. Mutations in the matrix (M) gene of VSV yield attenuated strains that may be very useful in both settings. As a result of this interest in the M protein, this study analysed various M–green fluorescent protein (GFP) fusion constructs. Remarkably, fusion of the N terminus of the M protein to GFP targeted the fluorescent protein to the surface of mitochondria. Mutational analysis indicated that a mitochondrial-targeting motif exists within aa 33–67. Expression of these fusion proteins led to loss of mitochondrial membrane permeability and to an alteration in mitochondrial organization mirroring that seen during viral infection. In addition, a portion of the M protein present in infected cells co-purified with mitochondria. This work may indicate a novel function for this multifunctional viral protein.

scholarly journals Nup98 Is a Mobile Nucleoporin with Transcription-dependent Dynamics

2002 ◽  
Vol 13 (4) ◽  
pp. 1282-1297 ◽  
Author(s):  
Eric R. Griffis ◽  
Nihal Altan ◽  
Jennifer Lippincott-Schwartz ◽  
Maureen A. Powers
Keyword(s):  
Binding Sites ◽  
Nuclear Export ◽  
Fluorescent Protein ◽  
Nuclear Pore ◽  
Amino Acid Repeat ◽  
Nuclear Trafficking ◽  
Rate Of Recovery ◽  
Green Fluorescent ◽  
Transport Factors

Nucleoporin 98 (Nup98), a glycine-leucine-phenylalanine-glycine (GLFG) amino acid repeat-containing nucleoporin, plays a critical part in nuclear trafficking. Injection of antibodies to Nup98 into the nucleus blocks the export of most RNAs. Nup98 contains binding sites for several transport factors; however, the mechanism by which this nucleoporin functions has remained unclear. Multiple subcellular localizations have been suggested for Nup98. Here we show that Nup98 is indeed found both at the nuclear pore complex and within the nucleus. Inside the nucleus, Nup98 associates with a novel nuclear structure that we term the GLFG body because the GLFG domain of Nup98 is required for targeting to this structure. Photobleaching of green fluorescent protein-Nup98 in living cells reveals that Nup98 is mobile and moves between these different localizations. The rate of recovery after photobleaching indicates that Nup98 interacts with other, less mobile, components in the nucleoplasm. Strikingly, given the previous link to nuclear export, the mobility of Nup98 within the nucleus and at the pore is dependent on ongoing transcription by RNA polymerases I and II. These data give rise to a model in which Nup98 aids in direction of RNAs to the nuclear pore and provide the first potential mechanism for the role of a mobile nucleoporin.

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