bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bacterial Lipopolysaccharide and Tumor Necrosis Factor Alpha Synergistically Increase Expression of Human Endothelial Adhesion Molecules through Activation of NF-κB and p38 Mitogen-Activated Protein Kinase Signaling Pathways
Authors: Jersmann Hubertus P. A. , Hii Charles S. T. , Ferrante Judith V. , Ferrante Antonio 
Published: July 2002

ABSTRACTOne of the recognized associations of bacterial infection with cardiovascular events is the activation of endothelium and upregulation of adhesion molecules. The two major proinflammatory mediators implicated in the causation of cardiovascular events, bacterial lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNF), were found to cooperate to enhance the adhesive properties of endothelial cells. These caused synergistic upregulation of intercellular adhesion molecule-1, E-selectin, and vascular cell adhesion molecule-1 in human umbilical vein endothelial cells as determined by flow cytometry analysis and enzyme-linked immunosorbent assay. This synergism was not due to TNF causing an upregulation of CD14 expression. Treatment with both LPS and TNF resulted in a marked increase in the translocation of NF-κB into the nucleus. The activity of p38 mitogen-activated protein kinase was also synergistically enhanced, while the activity of c-junN-terminal kinase was increased in an additive manner. The results demonstrate that LPS and TNF act synergistically to upregulate the expression of endothelial cell adhesion molecules, possibly by amplification of signaling pathways upstream of transcription. These findings have implications for the understanding of the acceleration of atherosclerotic events seen in low-grade infections with gram-negative organisms.
Circumvention of Herd Immunity during an Outbreak of Meningococcal Disease Could Be Correlated to Escape Mutation in the
porA
Gene of
Neisseria meningitidis
Authors: Taha Muhamed-Kheir , Bichier Edouard , Perrocheau Anne , Alonso Jean-Michel 
Published: July 2002

ABSTRACT

Meningococcal strains isolated during an outbreak were shown to belong to the ET-5 complex and to harbor a mutation in the VR2 region of the
porA
gene. They were less susceptible to the bactericidal effect of normal human serum than was the ET-5 wild-type strain. These results are of concern, as PorA is a potential target in vaccine design.
Human Monoclonal Antibodies againstPseudomonas aeruginosaLipopolysaccharide Derived from Transgenic Mice Containing Megabase Human Immunoglobulin Loci Are Opsonic and Protective against Fatal Pseudomonas Sepsis
Authors: Hemachandra Sonali , Kamboj Kulwant , Copfer Janna , Pier Gerald , Green Larry L. , Schreiber John R. 
Published: July 2002

ABSTRACTPseudomonas aeruginosais a significant human pathogen, and no vaccine is commercially available. Passive antibody prophylaxis using monoclonal antibodies (MAb) against protectiveP. aeruginosaepitopes is an alternative strategy for preventingP. aeruginosainfection, but mouse MAb are not suitable for use in humans. Polyclonal human antibodies from multiple donors have variable antibody titers, and human MAb are difficult to make. We used immunoglobulin-inactivated transgenic mice reconstituted with megabase-size human immunoglobulin loci to generate a human MAb against the polysaccharide (PS) portion of the lipopolysaccharide O side chain of a common pathogenic serogroup ofP. aeruginosa, 06ad. The anti-PS human immunoglobulin G2 MAb made from mice immunized with heat-killedP. aeruginosawas specific for serogroup 06ad pseudomonas. The MAb was highly opsonic for the uptake and killing ofP. aeruginosaby human polymorphonuclear leukocytes in the presence of human complement. In addition, 25 μg of the MAb protected 100% of neutropenic mice from fatalP. aeruginosasepsis. DNA sequence analysis of the genes encoding the MAb revealed VH3 and Vκ2/A2 variable-region genes, similar to variable-region genes in humans immunized with bacterial PS and associated with high-avidity anti-PS antibodies. We conclude that human MAb toP. aeruginosamade in these transgenic mice are highly protective and that these mice mimic the antibody response seen in humans immunized with T-cell-independent antigens such as bacterial PS.
Pasteurella multocida
Gene Expression in Response to Iron Limitation
Authors: Paustian Michael L. , May Barbara J. , Kapur Vivek 
Published: July 2002

ABSTRACT

Pasteurella multocida
is the causative agent of a wide range of diseases in avian and mammalian hosts. Gene expression in response to low iron conditions was analyzed in
P. multocida
using whole-genome microarrays. The analysis shows that the expression of genes involved in energy metabolism and electron transport generally decreased 2.1- to 6-fold while that of genes used for iron binding and transport increased 2.1- to 7.7-fold in
P. multocida
during the first 2 h of growth under iron-limiting conditions compared with controls. Notably, 27% of the genes with significantly altered expression had no known function, illustrating the limitations of using publicly available databases to identify genes involved in microbial metabolism and pathogenesis. Taken together, the results of our investigations demonstrate the utility of whole-genome microarray analyses for the identification of genes with altered expression profiles during varying growth conditions and provide a framework for the detailed analysis of the molecular mechanisms of iron acquisition and metabolism in
P. multocida
and other gram-negative bacteria.
Fresh Isolates from Children with SeverePlasmodium falciparumMalaria Bind to Multiple Receptors
Authors: Heddini Andreas , Pettersson Fredrik , Kai Oscar , Shafi Juma , Obiero Jack , Chen Qijun , Barragan Antonio , Wahlgren Mats , Marsh Kevin 
Published: July 2002

ABSTRACTThe sequestration ofPlasmodium falciparum-infected erythrocytes (pRBC) away from the peripheral circulation is a property of all field isolates. Here we have examined the pRBC of 111 fresh clinical isolates from children with malaria for a number of adhesive features in order to study their possible coexpression and association with severity of disease. A large number of adhesion assays were performed studying rosetting, giant rosetting, and binding to CD36, intercellular adhesion molecule 1, platelet endothelial cell adhesion molecule 1, thrombospondin, heparin, blood group A, and immunoglobulins. Suspension assays were performed at the actual parasitemia of the isolate, while all the static adhesion assays were carried out at an equal adjusted parasitemia. The ability to bind to multiple receptors, as well as the ability to form rosettes and giant rosettes, was found to be more frequent among isolates from children with severe versus mild malaria (P= 0.0015). Rosettes and giant rosettes were more frequent for children with severe malaria, and the cell aggregates were larger and tighter, than for those with mild disease (P= 0.0023). Binding of immunoglobulins (97% of isolates) and of heparin (81% of isolates) to infected erythrocytes was common, and binding to heparin and blood group A was associated with severity of disease (P= 0.011 andP= 0.031, respectively). These results support the idea that isolates that bind to multiple receptors are involved in the causation of severe malaria and that several receptor-ligand interactions work synergistically in bringing about severe disease.
Identification of a Transcytosis Epitope on Staphylococcal Enterotoxins
Authors: Shupp Jeffrey W. , Jett Marti , Pontzer Carol H. 
Published: July 2002

ABSTRACTStaphylococcal enterotoxins (SE) are exoproteins produced byStaphylococcus aureusthat act as superantigens and have been implicated as a leading cause of food-borne disease and toxic shock. Little is known about how these molecules penetrate the gut lining and gain access to both local and systemic immune tissues. To model movement in vitro of staphylococcal enterotoxins, we have employed a monolayer system composed of crypt-like human colonic T-84 cells. SEB and SEA showed comparable dose-dependent transcytosis in vitro, while toxic shock syndrome toxin (TSST-1) exhibited increased movement at lower doses. Synthetic peptides corresponding to specific regions of the SEB molecule were tested in vitro to identify the domain of the protein involved in the transcytosis of SE. A toxin peptide of particular interest contains the amino acid sequence KKKVTAQELD, which is highly conserved across all SE. At a toxin-to-peptide ratio of 1:10, movement of SEB across the monolayers was reduced by 85%. Antisera made against the SEB peptide recognized native SEB and also inhibited SEB transcytosis. Finally, the conserved 10-amino-acid peptide inhibited transcytosis of multiple staphylococcal enterotoxins, SEA, SEE, and TSST-1. These data demonstrate that this region of the staphylococcal enterotoxins plays a distinct role in toxin movement across epithelial cells. It has implications for the prevention of staphylococcal enterotoxin-mediated disease by design of a peptide vaccine that could reduce systemic exposure to oral or inhaled superantigens. Since the sequence identified is highly conserved, it allows for a single epitope blocking the transcytosis of multiple SE.
Human Secretory Immune Response to Fatty Acid-Binding Protein Fraction from
Giardia lamblia
Authors: Hasan S. M. T. , Maachee M. , Córdova O. M. , Diaz de la Guardia R. , Martins M. , Osuna A. 
Published: July 2002

ABSTRACT

The secretory immune response in humans infected with
Giardia lamblia
was studied by using saliva samples and an 8-kDa antigen capable of binding fatty acids. This antigen was not recognized by saliva samples from healthy individuals. The antigen may be useful in diagnostic studies of
G. lamblia
infection.
Inactivation of
gltB
Abolishes Expression of the Assimilatory Nitrate Reductase Gene (
nasB
) in
Pseudomonas putida
KT2442
Authors: Eberl Leo , Ammendola Aldo , Rothballer Michael H. , Givskov Michael , Sternberg Claus , Kilstrup Mogens , Schleifer Karl-Heinz , Molin Søren 
Published: July 2002

ABSTRACT

By using mini-Tn
5
transposon mutagenesis, random transcriptional fusions of promoterless bacterial luciferase,
luxAB
, to genes of
Pseudomonas putida
KT2442 were generated. Insertion mutants that responded to ammonium deficiency by induction of bioluminescence were selected. The mutant that responded most strongly was genetically analyzed and is demonstrated to bear the transposon within the assimilatory nitrate reductase gene (
nasB
) of
P. putida
KT2442. Genetic evidence as well as sequence analyses of the DNA regions flanking
nasB
suggest that the genes required for nitrate assimilation are not clustered. We isolated three second-site mutants in which induction of
nasB
expression was completely abolished under nitrogen-limiting conditions. Nucleotide sequence analysis of the chromosomal junctions revealed that in all three mutants the secondary transposon had inserted at different sites in the
gltB
gene of
P. putida
KT2442 encoding the major subunit of the glutamate synthase. A detailed physiological characterization of the
gltB
mutants revealed that they are unable to utilize a number of potential nitrogen sources, are defective in the ability to express nitrogen starvation proteins, display an aberrant cell morphology under nitrogen-limiting conditions, and are impaired in the capacity to survive prolonged nitrogen starvation periods.
Role of the
yiaR
and
yiaS
Genes of
Escherichia coli
in Metabolism of Endogenously Formed
l
-Xylulose
Authors: Ibañez Ester , Gimenez Rosa , Pedraza Tomas , Baldoma Laura , Aguilar Juan , Badia Josefa 
Published: July 2002

ABSTRACT

Genes
yiaP
and
yiaR
of the
yiaKLMNOPQRS
cluster of
Escherichia coli
are required for the metabolism of the endogenously formed
l
-xylulose, whereas
yiaS
is required for this metabolism only in
araD
mutants. Like AraD, YiaS was shown to have
l
-ribulose-5-phosphate 4-epimerase activity. Similarity of YiaR to several 3-epimerases suggested that this protein could catalyze the conversion of
l
-xylulose-5-phosphate into
l
-ribulose-5-phosphate, thus completing the pathway between
l
-xylulose and the general metabolism.
RNase III Processing of Intervening Sequences Found in Helix 9 of 23S rRNA in the Alpha Subclass of
Proteobacteria
Authors: Evguenieva-Hackenberg Elena , Klug Gabriele 
Published: July 2002

ABSTRACT

We provide experimental evidence for RNase III-dependent processing in helix 9 of the 23S rRNA as a general feature of many species in the alpha subclass of
Proteobacteria
(alpha-
Proteobacteria
). We investigated 12
Rhodobacter
,
Rhizobium
,
Sinorhizobium
,
Rhodopseudomonas
, and
Bartonella
strains. The processed region is characterized by the presence of intervening sequences (IVSs). The 23S rDNA sequences between positions 109 and 205 (
Escherichia coli
numbering) were determined, and potential secondary structures are proposed. Comparison of the IVSs indicates very different evolutionary rates in some phylogenetic branches, lateral genetic transfer, and evolution by insertion and/or deletion. We show that the IVS processing in
Rhodobacter capsulatus
in vivo is RNase III-dependent and that RNase III cleaves additional sites in vitro. While all IVS-containing transcripts tested are processed in vitro by RNase III from
R. capsulatus
,
E. coli
RNase III recognizes only some of them as substrates and in these substrates frequently cleaves at different scissile bonds. These results demonstrate the different substrate specificities of the two enzymes. Although RNase III plays an important role in the rRNA, mRNA, and bacteriophage RNA maturation, its substrate specificity is still not well understood. Comparison of the IVSs of helix 9 does not hint at sequence motives involved in recognition but reveals that the “antideterminant” model, which represents the most recent attempt to explain the
E. coli
RNase III specificity in vitro, cannot be applied to substrates derived from alpha-
Proteobacteria
.
Calcium and Malate Are Sporulation-Promoting Factors ofPhysarum polycephalum
Authors: Renzel Stefan , Esselborn Sigrid , Sauer Helmut W. , Hildebrandt Armin 
Published: July 2002

ABSTRACTFruiting body formation (sporulation) is a distinctive, irreversible differentiation process in the life cycle of the slime moldPhysarum polycephalum. The most important requirement for sporulation ofPhysarumis a period of starvation, and normally sporulation proceeds in the light. It is shown here that by omitting the liquid sporulation medium and elevating the temperature from 21 to 25°C, sporulation can occur routinely in the dark. It is further shown that this autocrine signaling in the dark requires calcium ions and malate. A putative sporulation control factor was detected in conditioned media derived from plasmodia starved in the dark, which was then identified as polymalate. As an additional role for this previously detected polyanion, specific for the plasmodial state ofPhysarum, it is suggested that the secreted compound serves as a source for both malate and calcium ions and thus promotes sporulation without light signaling.
Effects of Calcium and Calcium Chelators on Growth and Morphology of
Escherichia coli
L-Form NC-7
Authors: Onoda T. , Enokizono J. , Kaya H. , Oshima A. , Freestone P. , Norris V. 
Published: July 2002

ABSTRACT

Growth of a wall-less, L-form of
Escherichia coli
specifically requires calcium, and in its absence, cells ceased dividing, became spherical, swelled, developed large vacuoles, and eventually lysed. The key cell division protein, FtsZ, was present in the L-form at a concentration five times less than that in the parental strain. One interpretation of these results is that the L-form possesses an enzoskeleton partly regulated by calcium.
Genetic and Biochemical Characterization of the Pathway in
Pantoea citrea
Leading to Pink Disease of Pineapple
Authors: Pujol Catherine J. , Kado Clarence I. 
Published: July 2002

ABSTRACT

Pink disease of pineapple, caused by
Pantoea citrea
, is characterized by a dark coloration on fruit slices after autoclaving. This coloration is initiated by the oxidation of glucose to gluconate, which is followed by further oxidation of gluconate to as yet unknown chromogenic compounds. To elucidate the biochemical pathway leading to pink disease, we generated six coloration-defective mutants of
P. citrea
that were still able to oxidize glucose into gluconate. Three mutants were found to be affected in genes involved in the biogenesis of
c
-type cytochromes, which are known for their role as specific electron acceptors linked to dehydrogenase activities. Three additional mutants were affected in different genes within an operon that probably encodes a 2-ketogluconate dehydrogenase protein. These six mutants were found to be unable to oxidize gluconate or 2-ketogluconate, resulting in an inability to produce the compound 2,5-diketogluconate (2,5-DKG). Thus, the production of 2,5-DKG by
P. citrea
appears to be responsible for the dark color characteristic of the pink disease of pineapple.
A Common Regulator for the Operons Encoding the Enzymes Involved in
d
-Galactarate,
d
-Glucarate, and
d
-Glycerate Utilization in
Escherichia coli
Authors: Monterrubio Rafael , Baldoma Laura , Obradors Nuria , Aguilar Juan , Badia Josefa 
Published: July 2002

ABSTRACT

Genes for
d
-galactarate (
gar
) and
d
-glucarate (
gud
) metabolism in
Escherichia coli
are organized in three transcriptional units:
garD
,
garPLRK
, and
gudPD
. Two observations suggested a common regulator for the three operons. (i) Their expression was triggered by
d
-galactarate,
d
-glucarate, and
d
-glycerate. (ii) Metabolism of the three compounds was impaired by a single Tn
5
insertion mapped in the
yaeG
gene (proposed name,
sdaR
), outside the
d
-galactarate and
d
-glucarate systems. Expression of the
sdaR
gene is autogenously regulated.
p
-Hydroxyphenylacetic Acid Metabolism in
Pseudomonas putida
F6
Authors: O'Connor Kevin E. , Witholt Bernard , Duetz Wouter 
Published: July 2002

ABSTRACT

Pseudomonas putida
F6 was found to metabolize
p
-hydroxyphenylacetic acid through 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxymandelic acid, and 3,4-dihydroxybenzaldehyde. Cell extracts of
P. putida
F6 catalyze the NAD(P)H-independent hydroxylation of
p
-hydroxyphenylacetic acid to 3,4-dihydroxyphenylacetic acid which is further oxidized to 3,4-dihydroxymandelic acid. Oxidation and decarboxylation of the latter yields 3,4-dihydroxybenzaldehyde. A red-brown color accompanies all of the above enzyme activities and is probably due to the polymerization of quinone-like compounds. 3,4-Dihydroxybenzaldehyde is further metabolized through extradiol ring cleavage.
Properties and Mutation Analysis of the CelK Cellulose-Binding Domain from the
Clostridium thermocellum
Cellulosome
Authors: Kataeva Irina A. , Seidel Ronald D. , Li Xin-Liang , Ljungdahl Lars G. 
Published: July 2002

ABSTRACT

The family IV cellulose-binding domain of
Clostridium thermocellum
CelK (CBD
CelK
) was expressed in
Escherichia coli
and purified. It binds to acid-swollen cellulose (ASC) and bacterial microcrystalline cellulose (BMCC) with capacities of 16.03 and 3.95 μmol/g of cellulose and relative affinities (
K
r
) of 2.33 and 9.87 liters/g, respectively. The CBD
CelK
is the first representative of family IV CBDs to exhibit an affinity for BMCC. The CBD
CelK
also binds to the soluble polysaccharides lichenin, glucomannan, and barley β-glucan, which are substrates for CelK. It does not bind to xylan, galactomannan, and carboxymethyl cellulose. The CBD
CelK
contains 1 mol of calcium per mol. The CBD
CelK
has three thiol groups and one disulfide, reduction of which results in total loss of cellulose-binding ability. To reveal amino acid residues important for biological function of the domain and to investigate the role of calcium in the CBD
CelK
four highly conserved aromatic residues (Trp
56
, Trp
94
, Tyr
111
, and Tyr
136
) and Asp
192
were mutated into alanines, giving the mutants W56A, W94A, Y111A, Y136A, and D192A. In addition 14 N-terminal amino acids were deleted, giving the CBD-N
CelK
. The CBD-N
CelK
and D192A retained binding parameters close to that of the intact CBD
CelK
, W56A and W94A totally lost the ability to bind to cellulose, Y136A bound to both ASC and BMCC but with significantly reduced binding capacity and
K
r
and Y111A bound weakly to ASC and did not bind to BMCC. Mutations of the aromatic residues in the CBD
CelK
led to structural changes revealed by studying solubility, circular-dichroism spectra, dimer formation, and aggregation. Calcium content was drastically decreased in D192A. The results suggest that Asp192 is in the calcium-binding site of the CBD
CelK
and that calcium does not affect binding to cellulose. The 14 amino acids from the N terminus of the CBD
CelK
are not important for binding. Tyr136, corresponding to
Cellulomonas fimi
CenC CBD
N1
Y85, located near the binding cleft, might be involved in the formation of the binding surface, while Y111, W56A, and W94A are essential for the binding process by keeping the CBD
CelK
correctly folded.
Roles of
rpoN
,
fliA,
and
flgR
in Expression of Flagella in
Campylobacter jejuni
Authors: Jagannathan Aparna , Constantinidou Chrystala , Penn Charles W. 
Published: July 2002

ABSTRACT

Three potential regulators of flagellar expression present in the genome sequence of
Campylobacter jejuni
NCTC 11168, the genes
rpoN
,
flgR,
and
fliA,
which encode the alternative sigma factor ς
54
, the ς
54
-associated transcriptional activator FlgR, and the flagellar sigma factor ς
28
, respectively, were investigated for their role in global regulation of flagellar expression. The three genes were insertionally inactivated in
C. jejuni
strains NCTC 11168 and NCTC 11828. Electron microscopic studies of the wild-type and mutant strains showed that the
rpoN
and
flgR
mutants were nonflagellate and that the
fliA
mutant had truncated flagella. Immunoblotting experiments with the three mutants confirmed the roles of
rpoN
,
flgR,
and
fliA
in the expression of flagellin.
Site-Specific Integrative Elements of Rhizobiophage
16-3
Can Integrate into Proline tRNA (CGG) Genes in Different Bacterial Genera
Authors: Semsey Szabolcs , Blaha Béla , Köles Krisztián , Orosz László , Papp Péter P. 
Published: July 2002

ABSTRACT

The integrase protein of the
Rhizobium meliloti
41 phage
16-3
has been classified as a member of the Int family of tyrosine recombinases. The site-specific recombination system of the phage belongs to the group in which the target site of integration (
attB
) is within a tRNA gene. Since tRNA genes are conserved, we expected that the target sequence of the site-specific recombination system of the
16-3
phage could occur in other species and integration could take place if the required putative host factors were also provided by the targeted cells. Here we report that a plasmid (pSEM167) carrying the
attP
element and the integrase gene (
int
) of the phage can integrate into the chromosomes of
R. meliloti
1021 and eight other species. In all cases integration occurred at so-far-unidentified, putative proline tRNA (CGG) genes, indicating the possibility of their common origin. Multiple alignment of the sequences suggested that the location of the
att
core was different from that expected previously. The minimal
attB
was identified as a 23-bp sequence corresponding to the anticodon arm of the tRNA.