bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mga Is Sufficient To Activate Transcription In Vitro ofsof-sfbXand Other Mga-Regulated Virulence Genes in the Group A Streptococcus
Authors: Almengor Audry C. , Walters Matthew S. , McIver Kevin S. 
Published: March 2006

ABSTRACTThe group A streptococcus (GAS), orStreptococcus pyogenes, is a strict human pathogen of medical significance, causing infections ranging from pharyngitis (strep throat) to necrotizing fasciitis (flesh-eating disease). Several virulence genes that encode factors important for colonization, internalization, and immune evasion are under the control of the multiple gene regulator of the GAS, or Mga. Mga functions as a DNA-binding protein that interacts with sites both proximal (Pemmand PscpA) and distal (PsclA) to the start of transcription for the genes that it regulates. The genes encoding serum opacity factor,sof, and a novel fibronectin-binding protein,sfbX, are cotranscribed and represent two uncharacterized Mga-regulated virulence genes in the GAS. Analysis of the promoter region ofsof-sfbXidentified a putative Mga-binding site 278 bp upstream of the regulated start of transcription as determined by primer extension. Electrophoretic mobility shift assays demonstrated that Mga is able to bind specifically to the single distal site in a fashion similar to the previously characterized PsclA. In order to better understand the events that take place at this and other Mga-regulated promoters, an in vitro transcription assay was established. Using this assay, we showed that Mga is sufficient to activate transcription in vitro for Mga-regulated promoters containing both proximal (Pemm) and distal (PsclAand Psof-sfbX) binding sites. These results indicate that additional factors are not required for Mga-specific activation at diverse promoters in vitro, although they do not rule out the potential influence of other components on the Mga virulence regulon in vivo.
Requirement of
Staphylococcus aureus
ATP-Binding Cassette-ATPase FhuC for Iron-Restricted Growth and Evidence that It Functions with More than One Iron Transporter
Authors: Speziali Craig D. , Dale Suzanne E. , Henderson James A. , Vinés Enrique D. , Heinrichs David E. 
Published: March 2006

ABSTRACT

In
Staphylococcus aureus, fhuCBG
encodes an ATP-binding cassette (ABC) transporter that is required for the transport of iron(III)-hydroxamates; mutation of either
fhuB
or
fhuG
eliminates transport. In this paper, we describe construction and characterization of an
S. aureus fhuCBG
deletion strain. The Δ
fhuCBG
::
ermC
mutation not only resulted in a strain that was incapable of growth on iron(III)-hydroxamates as a sole source of iron but also resulted in a strain which had a profound growth defect in iron-restricted laboratory media. The growth defect was not a result of the inability to transport iron(III)-hydroxamates since
S. aureus fhuG
::Tn
917
and
S. aureus fhuD1
::Km
fhuD2
::Tet mutants, which are also unable to transport iron(III)-hydroxamates, do not have similar iron-restricted growth defects. Complementation experiments demonstrated that the growth defect of the Δ
fhuCBG
::
ermC
mutant was the result of the inability to express FhuC and that this was the result of an inability to transport iron complexed to the
S. aureus
siderophore staphylobactin. Transport of iron(III)-staphylobactin is dependent upon SirA (binding protein), SirB (permease), and SirC (permease).
S. aureus
expressing FhuC with a Walker A K42N mutation could not utilize iron(III)-hydroxamates or iron(III)-staphylobactin as a sole source of iron, supporting the conclusion that FhuC, as expected, functions with FhuB, FhuG, and FhuD1 or FhuD2 to transport iron(III)-hydroxamates and is the “genetically unlinked” ABC-ATPase that functions with SirA, SirB, and SirC to transport iron(III)-staphylobactin. Finally, we demonstrated that the Δ
fhuCBG
::
ermC
strain had decreased virulence in a murine kidney abscess model.
Abundance of the δ Subunit of RNA Polymerase Is Linked to the Virulence ofStreptococcus agalactiae
Authors: Seepersaud Ravin , Needham Rachel H. V. , Kim Cathy S. , Jones Amanda L. 
Published: March 2006

ABSTRACTGroup B streptococcus (GBS) remains a major cause of morbidity and mortality among newborn children. The bacterium is a commensal organism colonizing the rectum and the gastrointestinal and urogenital tracts of adults, but it can be transmitted to neonates by an ascending infection of the maternal genital tract or during parturition. We previously reported that a transposon insertion disruptingrpoEresulted in the decreased survival of the mutant in the neonatal rat sepsis model of GBS infection.rpoEencodes the δ protein, a subunit of RNA polymerase (RNAP) that has been characterized inBacillusspecies. In this study, we confirm the association of the δ protein with purified GBS RNAP and show that it is expressed in strains representing all nine serotypes. Flow cytometric analysis of a reporter strain containing a transcriptional fusion of therpoEpromoter togfprevealed that, in vitro, this gene is continuously expressed. Analysis of δ expression in the transposon mutant by quantitative Western blotting revealed a 10-fold reduction in relative abundance (which was linked to the attenuation in virulence that was observed for this mutant) compared to that for the wild-type strain. These data suggest that a minimum intracellular concentration of δ is necessary for this organism to cause disease.
Transcriptional and Biochemical Analysis of Starch Metabolism in the Hyperthermophilic Archaeon
Pyrococcus furiosus
Authors: Lee Han-Seung , Shockley Keith R. , Schut Gerrit J. , Conners Shannon B. , Montero Clemente I. , Johnson Matthew R. , Chou Chung-Jung , Bridger Stephanie L. , Wigner Nathan , Brehm Scott D. , Jenney Francis E. , Comfort Donald A. , Kelly Robert M. , Adams Michael W. W. 
Published: March 2006

ABSTRACT

Pyrococcus furiosus
utilizes starch and its degradation products, such as maltose, as primary carbon sources, but the pathways by which these α-glucans are processed have yet to be defined. For example, its genome contains genes proposed to encode five amylolytic enzymes (including a cyclodextrin glucanotransferase [CGTase] and amylopullulanase), as well as two transporters for maltose and maltodextrins (Mal-I and Mal-II), and a range of intracellular enzymes have been purified that reportedly metabolize maltodextrins and maltose. However, precisely which of these enzymes are involved in starch processing is not clear. In this study, starch metabolism in
P. furiosus
was examined by biochemical analyses in conjunction with global transcriptional response data for cells grown on a variety of glucans. In addition, DNA sequencing led to the correction of two key errors in the genome sequence, and these change the predicted properties of amylopullulanase (now designated PF1935*) and CGTase (PF0478*). Based on all of these data, a pathway is proposed that is specific for starch utilization that involves one transporter (Mal-II [PF1933 to PF1939]) and only three enzymes, amylopullulanase (PF1935*), 4-α-glucanotransferase (PF0272), and maltodextrin phosphorylase (PF1535). Their expression is upregulated on starch, and together they generate glucose and glucose-1-phosphate, which then feed into the novel glycolytic pathway of this organism. In addition, the results indicate that several hypothetical proteins encoded by three gene clusters are also involved in the transport and processing of α-glucan substrates by
P. furiosus
.
The Pea Nodule Environment Restores the Ability of a
Rhizobium leguminosarum
Lipopolysaccharide
acpXL
Mutant To Add 27-Hydroxyoctacosanoic Acid to Its Lipid A
Authors: Vedam Vinata , Kannenberg Elmar , Datta Anup , Brown Dusty , Haynes-Gann Janine G. , Sherrier D. Janine , Carlson Russell W. 
Published: March 2006

ABSTRACT

Members of the
Rhizobiaceae
contain 27-hydroxyoctacosanoic acid (27OHC
28:0
) in their lipid A. A
Rhizobium leguminosarum 3841 acpXL
mutant (named here Rlv22) lacking a functional specialized acyl carrier lacked 27OHC
28:0
in its lipid A, had altered growth and physiological properties (e.g., it was unable to grow in the presence of an elevated salt concentration [0.5% NaCl]), and formed irregularly shaped bacteroids, and the synchronous division of this mutant and the host plant-derived symbiosome membrane was disrupted. In spite of these defects, the mutant was able to persist within the root nodule cells and eventually form, albeit inefficiently, nitrogen-fixing bacteroids. This result suggested that while it is in a host root nodule, the mutant may have some mechanism by which it adapts to the loss of 27OHC
28:0
from its lipid A. In order to further define the function of this fatty acyl residue, it was necessary to examine the lipid A isolated from mutant bacteroids. In this report we show that addition of 27OHC
28:0
to the lipid A of Rlv22 lipopolysaccharides is partially restored in Rlv22
acpXL
mutant bacteroids. We hypothesize that
R. leguminosarum
bv. viciae 3841 contains an alternate mechanism (e.g., another
acp
gene) for the synthesis of 27OHC
28:0
, which is activated when the bacteria are in the nodule environment, and that it is this alternative mechanism which functionally replaces
acpXL
and is responsible for the synthesis of 27OHC
28:0
-containing lipid A in the Rlv22
acpXL
bacteroids.
MprAB Is a Stress-Responsive Two-Component System That Directly Regulates Expression of Sigma Factors SigB and SigE in
Mycobacterium tuberculosis
Authors: He Hongjun , Hovey Raymond , Kane Jason , Singh Vineet , Zahrt Thomas C. 
Published: March 2006

ABSTRACT

The genetic mechanisms mediating the adaptation of
Mycobacterium tuberculosis
within the host are poorly understood. The best-characterized regulatory systems in this organism include sigma factors and two-component signal transduction systems.
mprAB
is a two-component system required by
M. tuberculosis
for growth in vivo during the persistent stage of infection. In this report, we demonstrate that MprAB is stress responsive and regulates the expression of numerous stress-responsive genes in
M. tuberculosis
. With DNA microarrays and quantitative real-time reverse transcription-PCR, genes regulated by MprA in
M. tuberculosis
that included two stress-responsive sigma factors were identified. Response regulator MprA bound to conserved motifs in the upstream regions of both
sigB
and
sigE
in vitro and regulated the in vivo expression of
sigB
and
sigE
in
M. tuberculosis
. In addition,
mprA
itself was induced following exposure to stress, establishing a direct role for this regulatory system in stress response pathways of
M. tuberculosis
. Induction of
mprA
and
sigE
by MprA in response to stress was mediated through the cognate sensor kinase MprB and required expression of the extracytoplasmic loop domain. These results provide the first evidence that recognition of and adaptation to specific stress in
M. tuberculosis
are mediated through activation of a two-component signal transduction system that directly regulates the expression of stress-responsive determinants.
Regulation of Long-Chain
N
-Acyl-Homoserine Lactones in
Agrobacterium vitis
Authors: Hao Guixia , Burr Thomas J. 
Published: March 2006

ABSTRACT

Homologs of quorum-sensing
luxR
and
luxI
regulatory genes,
avsR
and
avsI
, were identified in
Agrobacterium vitis
strain F2/5. Compared to other LuxI proteins from related species, the deduced AvsI shows the greatest identity to SinI (71%) from
Sinorhizobium meliloti
Rm1021. AvsR possesses characteristic autoinducer binding and helix-turn-helix DNA binding domains and shares a high level of identity with SinR (38%) from Rm1021. Site-directed mutagenesis of
avsR
and
avsI
was performed, and both genes are essential for hypersensitive-like response (HR) and necrosis. Two hypothetical proteins (ORF1 and ORF2) that are positioned downstream of
avsR-avsI
are also essential for the phenotypes. Profiles of
N
-acyl-homoserine lactones (AHLs) isolated from the wild type and mutants revealed that disruption of
avsI
, ORF1, or ORF2 abolished the production of long-chain AHLs. Disruption of
avsR
reduces long-chain AHLs. Expression of a cloned
avsI
gene in
A. tumefaciens
strain NT1 resulted in synthesis of long-chain AHLs. The necrosis and HR phenotypes of the
avsI
and
avsR
mutants were fully complemented with cloned
avsI
. The addition of synthetic AHLs (C
16:1
and 3-O-C
16:1
) complemented grape necrosis in the
avsR
,
avsI
, ORF1, and ORF2 mutants. It was determined by reverse transcriptase PCR that the expression level of
avsI
is regulated by
avsR
but not by
aviR
or
avhR
, two other luxR homologs which were previously shown to be associated with induction of a tobacco hypersensitive response and grape necrosis. We further verified that
avsR
regulates
avsI
by measuring the expression of an
avsI
::
lacZ
fusion construct.
YtkD and MutT Protect Vegetative Cells but Not Spores of
Bacillus subtilis
from Oxidative Stress
Authors: Castellanos-Juárez Francisco X. , Álvarez-Álvarez Carlos , Yasbin Ronald E. , Setlow Barbara , Setlow Peter , Pedraza-Reyes Mario 
Published: March 2006

ABSTRACT

ytkD
and
mutT
of
Bacillus subtilis
encode potential 8-oxo-dGTPases that can prevent the mutagenic effects of 8-oxo-dGTP. Loss of YtkD but not of MutT increased the spontaneous mutation frequency of growing cells. However, cells lacking both YtkD and MutT had a higher spontaneous mutation frequency than cells lacking YtkD. Loss of either YtkD or MutT sensitized growing cells to hydrogen peroxide (H
2
O
2
) and
t
-butylhydroperoxide (
t
-BHP), and the lack of both proteins sensitized growing cells to these agents even more. In contrast,
B. subtilis
spores lacking YtkD and MutT were not sensitized to H
2
O
2
,
t
-BHP, or heat. These results suggest (i) that YtkD and MutT play an antimutator role and protect growing cells of
B. subtilis
against oxidizing agents, and (ii) that neither YtkD nor MutT protects spores against potential DNA damage induced by oxidative stress or heat.
Genomic Comparison of
Mycobacterium avium
subsp.
paratuberculosis
Sheep and Cattle Strains by Microarray Hybridization
Authors: Marsh Ian B. , Bannantine John P. , Paustian Michael L. , Tizard Mark L. , Kapur Vivek , Whittington Richard J. 
Published: March 2006

ABSTRACT

Microarray-based comparisons of three
Mycobacterium avium
subsp.
paratuberculosis
isolates, including one sheep strain and two cattle strains, identified three large genomic deletions in the sheep strain, totaling 29,208 bp and involving 24 open reading frames. These deletions may help explain some of the differences in pathogenicity and host specificity observed between the cattle and sheep strains of
Mycobacterium avium
subsp.
paratuberculosis
.
Loss of Fragile Histidine Triad Gene Expression in Advanced Lung Cancer Is Consequent to Allelic Loss at 3p14 Locus and Promoter Methylation
Authors: Wali Anjilna , Srinivasan Radhika , Shabnam Mir Snober , Majumdar Siddhartha , Joshi Kusum , Behera Digambar 
Published: March 2006

Abstract
The fragile histidine triad (FHIT) gene located at the 3p14.2 locus plays an important role in the pathogenesis of lung cancer. The objective of this study was to analyze loss of heterozygosity and FHIT gene methylation status and correlate them to fhit expression. Bronchoscopically obtained lung biopsies from 30 cases of histologically proven carcinoma of the lung in stage III were assessed for the alterations in the FHIT gene. Fhit protein expression was determined by immunohistochemistry, and transcript levels were determined by reverse transcription-PCR. Microsattelite alterations and methylation status of the Fhit gene promoter was determined by PCR. Loss of heterozygosity at the 3p14 locus was observed in all the 30 cases at least by one of the three microsatellite polymorphic markers. The FHIT gene promoter showed complete methylation in 37% cases and partial methylation in 47% cases, and 16% cases showed no promoter methylation. FHIT full-length coding region (exons 5-9) transcripts were present in eight cases (26.6%), and aberrant transcripts were additionally seen in four cases. Loss of FHIT mRNA expression correlated to FHIT promoter methylation but not to loss of heterozygosity at the 3p14 locus. There was a strong correlation between the expression of FHIT at the transcript and protein level. The apoptotic index estimated by the terminal deoxynucleotidyl transferase–mediated nick end labeling assay was significantly correlated to the fhit protein expression. The results of this study indicate that in locally advanced carcinoma of the lung, there is frequent loss of FHIT expression, and methylation of the FHIT gene promoter is an important mechanism of its inactivation. (Mol Cancer Res 2006;4(2):93–9)
Mechanisms of Cell Death Induced by Histone Deacetylase Inhibitors in Androgen Receptor–Positive Prostate Cancer Cells
Authors: Rokhlin Oskar W. , Glover Rebecca B. , Guseva Natalya V. , Taghiyev Agshin F. , Kohlgraf Karl G. , Cohen Michael B. 
Published: March 2006

Abstract
Histone deacetylase inhibitors (HDACI) are potential therapeutic agents that inhibit tumor cell growth and survival. Although there are several publications regarding the effects of HDACIs on prostate cancer cell growth, their mechanism(s) of action remains undefined. We treated several human prostate cancer cell lines with the HDACI trichostatin A and found that trichostatin A induced cell death in androgen receptor (AR)–positive cell lines to higher extent compared with AR-negative cell lines. We then discovered that trichostatin A and other HDACIs suppressed AR gene expression in prostate cancer cell lines as well as in AR-positive breast carcinoma cells and in mouse prostate. Trichostatin A also induced caspase activation, but trichostatin A–induced AR suppression and cell death were caspase independent. In addition, we found that doxorubicin inhibited AR expression, and p21 protein completely disappeared after simultaneous treatment with trichostatin A and doxorubicin. This effect may be attributed to the induction of protease activity under simultaneous treatment with these two agents. Further, simultaneous treatment with trichostatin A and doxorubicin increased cell death in AR-positive cells even after culturing in steroid-free conditions. The protease/proteasome inhibitor MG132 protected AR and p21 from the effects of trichostatin A and doxorubicin and inhibited trichostatin A–induced cell death in AR-positive prostate cells. Taken together, our data suggest that the main mechanism of trichostatin A–induced cell death in AR-positive prostate cancer is inhibition of AR gene expression. The synergistic effect of simultaneous treatment with trichostatin A and doxorubicin is mediated via inhibition of AR expression, induction of protease activity, increased expression of p53, and proteolysis of p21. (Mol Cancer Res 2006;4(2):113–23)
Involvement of the ATR- and ATM-Dependent Checkpoint Responses in Cell Cycle Arrest Evoked by Pierisin-1
Authors: Shiotani Bunsyo , Kobayashi Masahiko , Watanabe Masahiko , Yamamoto Ken-ichi , Sugimura Takashi , Wakabayashi Keiji 
Published: March 2006

Abstract
Pierisin-1 identified from the cabbage butterfly, Pieris rapae, is a novel mono-ADP-ribosylating toxin that transfers the ADP-ribose moiety of NAD at N2 of dG in DNA. Resulting mono-ADP-ribosylated DNA adducts cause mutations and the induction of apoptosis. However, little is known about checkpoint responses elicited in mammalian cells by the formation of such bulky DNA adducts. In the present study, it was shown that DNA polymerases were blocked at the specific site of mono-ADP-ribosylated dG, which might lead to the replication stress. Pierisin-1 treatment of HeLa cells was found to induce an intra-S-phase arrest through both ataxia telangiectasia mutated (ATM) and Rad3-related (ATR) and ATM pathways, and ATR pathway also contributes to a G2-M-phase delay. In the colony survival assays, Rad17−/− DT40 cells showed greater sensitivity to pierisin-1-induced cytotoxicity than wild-type and ATM−/− DT40 cells, possibly due to defects of checkpoint responses, such as the Chk1 activation. Furthermore, apoptotic 50-kb DNA fragmentation was observed in the HeLa cells, which was well correlated with occurrence of phosphorylation of Chk2. These results thus suggest that pierisin-1 treatment primarily activates ATR pathway and eventually activates ATM pathway as a result of the induction of apoptosis. From these findings, it is suggested that mono-ADP-ribosylation of DNA causes a specific type of fork blockage that induces checkpoint activation and signaling. (Mol Cancer Res 2006;4(2):125–33)
Disarmament without Agreements?
Authors: Rydell Randy 
Published: March 2006

AbstractThe literature on arms control and disarmament is replete with studies demonstrating the numerous difficulties in negotiating agreements for the control or elimination of nuclear weapons. These studies stress the time consumed during negotiations, the complexity of the emerging agreements, the trade-offs required to achieve agreement, the political difficulties of treaty ratification, and the alleged advantages of alternative approaches to arms control and disarmament not involving treaties. This essay examines whether treaties and negotiations are in fact dispensable in achieving agreed multilateral disarmament objectives. It surveys recent multilateral efforts in the field of nuclear disarmament and identifies six basic criteria that enjoy broad international support as standards for assessing the merits of disarmament agreements. The essay concludes that tacit understandings and other informal political arrangements offer no substitute for legally-binding treaty obligations. This conclusion leads to several implications affecting the conduct of multilateral negotiations, and the kinds of institutional support required in the negotiating process and for the maintenance of key commitments by the relevant multilateral regimes.
Negotiating Multilateral Instruments Against Missile Proliferation
Authors: Mistry Dinshaw , Smith Mark 
Published: March 2006

AbstractThe absence of a major multilateral treaty banning missiles is explained by the limited scope of the two main instruments against missile proliferation – the Missile Technology Control Regime (MTCR) and the Hague Code of Conduct against Ballistic Missile Proliferation (HCOC). In the MTCR's case, limiting the scope to supply-side technology controls facilitated progress during its negotiations. In the Hague Code, limiting the scope to transparency, and keeping out additional items such as incentives to renounce ballistic missiles and the topic of cruise missiles, made negotiations easier. The trade-off from a limited scope in both instruments is that there is still no significant worldwide treaty banning missiles.