bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonopsonic Binding of Type III Group B Streptococci to Human Neutrophils Induces Interleukin-8 Release Mediated by the p38 Mitogen-Activated Protein Kinase Pathway
Authors: Albanyan Esam A. , Vallejo Jesus G. , Smith C. Wayne , Edwards Morven S. 
Published: July 2002

ABSTRACTNonopsonic interaction of host immune cells with pathogens is an important first line of defense. We hypothesized that nonopsonic recognition between type III group B streptococcus and human neutrophils would occur and that the interaction would be sufficient to trigger neutrophil activation. By using a serum-free system, it was found that heat-killed type III group B streptococci bound to neutrophils in a rapid, stable, and inoculum-dependent manner that did not result in ingestion. Transposon-derived type III strain COH1-13, which lacks capsular polysaccharide, and strain COH1-11 with capsular polysaccharide lacking terminal sialic acid demonstrated increased neutrophil binding, suggesting that capsular polysaccharide masks an underlying binding site. Experiments using monoclonal antibodies to complement receptor 1 and to the I domain or lectin site of complement receptor 3 did not inhibit binding, indicating that the complement receptors used for ingestion of opsonized group B streptococci were not required for nonopsonic binding. Nonopsonic binding resulted in rapid activation of cellular p38 and p44/42 mitogen-activated protein kinases. This interaction was not an effective trigger for superoxide production but did promote release of the proinflammatory cytokine interleukin-8. The release of interleukin-8 was markedly suppressed by the p38 mitogen-activated protein kinase inhibitor SB203580 but was only minimally suppressed by the mitogen-activated protein/extracellular signal-regulated kinase inhibitor PD98059. Thus, nonopsonic binding of type III group B streptococci to neutrophils is sufficient to initiate intracellular signaling pathways and could serve as an arm of innate immunity of particular importance to the immature host.
Identification of a Human Lactoferrin-Binding Protein in
Gardnerella vaginalis
Authors: Jarosik Gregory P. , Land Carol Beth 
Published: July 2002

ABSTRACT

Previous studies have shown that
Gardnerella vaginalis
can utilize iron-loaded human lactoferrin as a sole source of iron. In this study,
G. vaginalis
cells were shown to bind digoxigenin (DIG)-labeled human lactoferrin in a dot blot assay. Using the DIG-labeled human lactoferrin, a 120-kDa human lactoferrin-binding protein was detected by Western blot analysis of
G. vaginalis
proteins. The lactoferrin-binding activity of this protein was found to be heat stable. Competition studies indicated that this binding activity was specific for human lactoferrin. Treatment of
G. vaginalis
cells with proteases suggested that this protein was surface exposed. An increase in lactoferrin binding by the 120-kDa protein was observed in
G. vaginalis
cells grown under iron-restrictive conditions, suggesting that this activity may be iron regulated.
Gamma Interferon Is Essential for Clearing
Mycobacterium genavense
Infection
Authors: Ehlers Stefan , Richter Elvira 
Published: July 2002

ABSTRACT

Factors determining the in vivo replication of the opportunistic pathogen
Mycobacterium genavense
are largely unknown. Following intravenous injection of a patient isolate,
M. genavense
could not be recovered by culture or detected by PCR in the livers or spleens of infected BALB/c mice. In contrast,
M. genavense
was found to chronically persist and multiply in the livers and spleens of intravenously infected syngeneic gamma-interferon-gene-deficient (GKO) mice as evidenced by acid-fast stains of infected tissues and recovery by both PCR and liquid culture following organ homogenization. In GKO mice,
M. genavense
elicited a chronic inflammatory response, resulting in marked splenomegaly and extensive lymphadenopathy. Granulomatous lesions in the livers of GKO mice were diffuse, were composed of monocytes, neutrophils, and CD3
+
cells, and were histochemically negative for inducible nitric oxide synthase.
Identification of a Novel Gene Cluster Encoding Staphylococcal Exotoxin-Like Proteins: Characterization of the Prototypic Gene and Its Protein Product, SET1
Authors: Williams Rachel J. , Ward John M. , Henderson Brian , Poole Stephen , O'Hara Bernard P. , Wilson Michael , Nair Sean P. 
Published: July 2002

ABSTRACTWe report the discovery of a novel genetic locus withinStaphylococcus aureusthat encodes a cluster of at least five exotoxin-like proteins. Designated the staphylococcal exotoxin-like genes 1 to 5 (set1toset5), these open reading frames have between 38 and 53% homology to each other. All five proteins contain consensus sequences that are found in staphylococcal and streptococcal exotoxins and toxic shock syndrome toxin 1 (TSST-1). However, the SETs have only limited overall sequence homology to the enterotoxins and TSST-1 and thus represent a novel family of exotoxin-like proteins. The prototypic gene in this cluster,set1, has been cloned and expressed. Recombinant SET1 stimulated the production of interleukin-1β, interleukin-6, and tumor necrosis factor alpha by human peripheral blood mononuclear cells. PCR analysis revealed thatset1was distributed among other strains ofS. aureusbut not in the other staphylococcal species examined. Sequence analysis of theset1genes from different strains revealed at least three allelic variants. The protein products of these allelic variants displayed a 100-fold difference in their cytokine-inducing potency. The distribution of allelic variants of thesetgenes among strains ofS. aureusmay contribute to differences in the pathogenic potential of this bacterium.
Evaluation of Phase Variation of Nontypeable
Haemophilus influenzae
Lipooligosaccharide during Nasopharyngeal Colonization and Development of Otitis Media in the Chinchilla Model
Authors: Tong H. H. , Blue L. E. , James M. A. , Chen Y. P. , DeMaria T. F. 
Published: July 2002

ABSTRACT

Nontypeable
Haemophilus influenzae
(NTHI) has four loci,
lic-1
to
lic-3
and
lgtC
, that generate phase-variable lipooligosaccharide (LOS) structures.
lic-1
, which is required for the expression of phosphorylcholine (ChoP), is the best characterized and is associated with an enhanced ability of
H. influenzae
to persist within the nasopharynges of infant rats. Recent data indicate that LOS impacts various aspects of NTHI virulence in the chinchilla model of nasopharyngeal colonization and otitis media (OM). In this study the effects of ChoP expression and the sequences of
lic-1
to
lic-3
and
lgtC
of NTHI strain 2019 were evaluated in the chinchilla OM model. Nasopharyngeal colonization data showed that a switch from the ChoP
−
to the ChoP
+
phenotype was observed as early as day 3 after intranasal inoculation. Chinchillas colonized by strains with the ChoP
+
phenotype demonstrated a significantly higher level of NTHI 2019 per milliliter of nasal lavage fluid than chinchillas colonized with predominantly the ChoP
−
variant (
P
< 0.05). The concentration of cells with the ChoP
+
phenotype in the middle ear was 3 log units higher than that of cells with the ChoP
−
variant (
P
< 0.01). There was a statistically significant association between ChoP
+
expression in the nasal lavage and the development of OM with culture-positive middle ear fluids in this model. These data suggest that expression of the ChoP
+
phenotype promotes enhanced nasopharyngeal colonization and development of OM.
Role of Mannoprotein in Induction and Regulation of Immunity toCryptococcus neoformans
Authors: Pietrella Donatella , Cherniak Robert , Strappini Carla , Perito Stefano , Mosci Paolo , Bistoni Francesco , Vecchiarelli Anna 
Published: July 2002

ABSTRACTOur previous observations showed that mannoprotein (MP) induces early and massive production of interleukin-12 (IL-12) in vitro. This study was designed to investigate whether this phenomenon could be applied in vivo and to determine the biological significance of MP inCryptococcus neoformansinfection. The results reported here show that MP treatment induces IL-12 secretion by splenic macrophages and IL-12 p40 mRNA in the brain. DuringC. neoformansinfection, MP reinforced IL-12 and IFN-γ secretion that coincided with enhanced antifungal activity of natural effector cells, early resolution of the inflammatory process, and clearance of fungal load from the brain. These studies show that MP is a key inflammatory mediator that induces a protective immune response againstC. neoformansinfection. This information can be used to facilitate the design of a rational approach to manipulate the immune response toC. neoformans.
Ligand-Binding Properties of the Carboxyl-Terminal Repeat Domain of
Streptococcus mutans
Glucan-Binding Protein A
Authors: Haas Wolfgang , Banas Jeffrey A. 
Published: July 2002

ABSTRACT

Streptococcus mutans
glucan-binding protein A (GbpA) has sequence similarity in its carboxyl-terminal domain with glucosyltransferases (GTFs), the enzymes responsible for catalyzing the synthesis of the glucans to which GbpA and GTFs can bind and which promote
S. mutans
attachment to and accumulation on the tooth surface. It was predicted that this C-terminal region, comprised of what have been termed YG repeats, represents the GbpA glucan-binding domain (GBD). In an effort to test this hypothesis and to quantitate the ligand-binding specificities of the GbpA GBD, several fusion proteins were generated and tested by affinity electrophoresis or by precipitation of protein-ligand complexes, allowing the determination of binding constants. It was determined that the 16 YG repeats in GbpA comprise its GBD and that GbpA has a greater affinity for dextran (a water-soluble form of glucan) than for mutan (a water-insoluble form of glucan). Placement of the GBD at the carboxyl terminus was necessary for maximum glucan binding, and deletion of as few as two YG repeats from either end of the GBD reduced the affinity for dextran by over 10-fold. Interestingly, the binding constant of GbpA for dextran was 34-fold higher than that calculated for the GBDs of two
S. mutans
GTFs, one of which catalyzes the synthesis of water-soluble glucan and the other of which catalyzes the synthesis of water-insoluble glucan.
Autophosphorylation of Phosphoglucosamine Mutase from
Escherichia coli
Authors: Jolly Laure , Pompeo Frédérique , van Heijenoort Jean , Fassy Florence , Mengin-Lecreulx Dominique 
Published: July 2002

ABSTRACT

Phosphoglucosamine mutase (GlmM) catalyzes the formation of glucosamine-1-phosphate from glucosamine-6-phosphate, an essential step in the pathway for UDP-
N
-acetylglucosamine biosynthesis in bacteria. This enzyme must be phosphorylated to be active and acts according to a ping-pong mechanism involving glucosamine-1,6-diphosphate as an intermediate (L. Jolly, P. Ferrari, D. Blanot, J. van Heijenoort, F. Fassy, and D. Mengin-Lecreulx, Eur. J. Biochem. 262:202–210, 1999). However, the process by which the initial phosphorylation of the enzyme is achieved in vivo remains unknown. Here we show that the phosphoglucosamine mutase from
Escherichia coli
autophosphorylates in vitro in the presence of [
32
P]ATP. The same is observed with phosphoglucosamine mutases from other bacterial species, yeast
N
-acetylglucosamine-phosphate mutase, and rabbit muscle phosphoglucomutase. Labeling of the
E. coli
GlmM enzyme with [
32
P]ATP requires the presence of a divalent cation, and the label is subsequently lost when the enzyme is incubated with either of its substrates. Analysis of enzyme phosphorylation by high-pressure liquid chromatography and coupled mass spectrometry confirms that only one phosphate has been covalently linked to the enzyme. Only phosphoserine could be detected after acid hydrolysis of the labeled protein, and site-directed mutagenesis of serine residues located in or near the active site identifies the serine residue at position 102 as the site of autophosphorylation of
E. coli
GlmM.
A Novel Spore Peptidoglycan Hydrolase of
Bacillus cereus
: Biochemical Characterization and Nucleotide Sequence of the Corresponding Gene,
sleL
Authors: Chen Yinghua , Fukuoka Satoshi , Makino Shio 
Published: July 2002

ABSTRACT

The exudate of germinated spores of
B. cereus
IFO 13597 in 0.15 M KCl–50 mM potassium phosphate (pH 7.0) contained a spore-lytic enzyme which has substrate specificity for fragmented spore cortex from wild-type organisms (cortical-fragment-lytic enzyme [CFLE]), in addition to a previously characterized germination-specific hydrolase which acts on intact spore cortex (spore cortex-lytic enzyme [SCLE]) (R. Moriyama, S. Kudoh, S. Miyata, S. Nonobe, A. Hattori, and S. Makino, J. Bacteriol. 178:5330–5332, 1996). CFLE was not capable of degrading isolated cortical fragments from spores of
Bacillus subtilis
ADD1, which lacks muramic acid δ-lactam. This suggests that CFLE cooperates with SCLE in cortex hydrolysis during germination. CFLE was purified in an active form and identified as a 48-kDa protein which functions as an
N
-acetylglucosaminidase. Immunochemical studies suggested that the mature enzyme is localized on a rather peripheral region of the dormant spore, probably the exterior of the cortex layer. A gene encoding the enzyme,
sleL
, was cloned in
Escherichia coli
, and the nucleotide sequence was determined. The gene encodes a protein of 430 amino acids with a deduced molecular weight of 48,136. The N-terminal region contains a repeated motif common to several peptidoglycan binding proteins. Inspection of the data banks showed no similarity of CFLE with
N
-acetylglucosaminidases found so far, suggesting that CFLE is a novel type of
N
-acetylglucosaminidase. The
B. subtilis
genome sequence contains genes,
yaaH
and
ydhD
, which encode putative proteins showing similarity to SleL.
Activities of
virE1
and the VirE1 Secretion Chaperone in Export of the Multifunctional VirE2 Effector via an
Agrobacterium
Type IV Secretion Pathway
Authors: Zhao Zhenming , Sagulenko Evgeniy , Ding Zhiyong , Christie Peter J. 
Published: July 2002

ABSTRACT

Agrobacterium tumefaciens
uses a type IV secretion system to deliver oncogenic nucleoprotein particles and effector proteins, such as the multifunctional VirE2 protein, to plant cells. In this study, we examined the function of
virE1
and its product, the VirE1 secretion chaperone, in mediating VirE2 export. A nonpolar
virE1
null mutant accumulated low levels of VirE2, and
trans
expression of
virE1
in this mutant only partially restored VirE2 abundance. Deletion of
virE1
did not affect transcription but decreased translation of
virE2
, as shown by analysis of
lacZ
transcriptional and translational fusions. VirE2 was stable for a prolonged period, more than 6 h, when it was expressed in
cis
with
virE1
, and it exhibited half-lives of about 2 h when it was expressed in
trans
with
virE1
and less than 10 min when it was expressed in the absence of
virE1
, as shown by pulse-chase experiments. VirE1 stabilized VirE2 via an interaction with a domain near the N terminus of VirE2, as shown by analyses of VirE2 truncation and insertion mutants synthesized in
A. tumefaciens
. VirE1 self-association was demonstrated by using bacteriophage λ cI repressor fusion and pull-down assays, and evidence of VirE1 homomultimerization in vivo was obtained by native polyacrylamide gel electrophoresis and gel filtration chromatography. A putative VirE1-VirE2 complex with a molecular mass of about 70 to 80 kDa was detected by gel filtration chromatography of extracts from wild-type cells, whereas higher-order VirE2 complexes or aggregates were detected in extracts from a
virE1
mutant. Taken together, our findings show that
virE1
contributes in several ways to VirE2 export:(i)
virE1
regulates efficient
virE2
translation in the context of expression from the native

P
virE

promoter; (ii) the VirE1 secretion chaperone stabilizes VirE2, most probably via an interaction with an N-terminal domain; and (iii) VirE1 forms a VirE1-VirE2 complex with a predicted 2:1 stoichiometry that inhibits assembly of higher-order VirE2 complexes or aggregates.
Diversity of
Streptococcus salivarius ptsH
Mutants That Can Be Isolated in the Presence of 2-Deoxyglucose and Galactose and Characterization of Two Mutants Synthesizing Reduced Levels of HPr, a Phosphocarrier of the Phosphoenolpyruvate:Sugar Phosphotransferase System
Authors: Thomas Suzanne , Brochu Denis , Vadeboncoeur Christian 
Published: July 2002

ABSTRACT

In streptococci, HPr, a phosphocarrier of the phosphoenolpyruvate:sugar phosphotransferase transport system (PTS), undergoes multiple posttranslational chemical modifications resulting in the formation of HPr(His∼P), HPr(Ser-P), and HPr(Ser-P)(His∼P), whose cellular concentrations vary with growth conditions. Distinct physiological functions are associated with specific forms of HPr. We do not know, however, the cellular thresholds below which these forms become unable to fulfill their functions and to what extent modifications in the cellular concentrations of the different forms of HPr modify cellular physiology. In this study, we present a glimpse of the diversity of
Streptococcus salivarius ptsH
mutants that can be isolated by positive selection on a solid medium containing 2-deoxyglucose and galactose and identify 13 amino acids that are essential for HPr to properly accomplish its physiological functions. We also report the characterization of two
S. salivarius
mutants that produced approximately two- and threefoldless HPr and enzyme I (EI) respectively. The data indicated that (i) a reduction in the synthesis of HPr due to a mutation in the Shine-Dalgarno sequence of
ptsH
reduced
ptsI
expression; (ii) a threefold reduction in EI and HPr cellular levels did not affect PTS transport capacity; (iii) a twofold reduction in HPr synthesis was sufficient to reduce the rate at which cells metabolized PTS sugars, increase generation times on PTS sugars and to a lesser extent on non-PTS sugars, and impede the exclusion of non-PTS sugars by PTS sugars; (iv) a threefold reduction in HPr synthesis caused a strong derepression of the genes coding for α-galactosidase, β-galactosidase, and galactokinase when the cells were grown at the expense of a PTS sugar but did not affect the synthesis of α-galactosidase when cells were grown at the expense of lactose, a noninducing non-PTS sugar; and (v) no correlation was found between the magnitude of enzyme derepression and the cellular levels of HPr(Ser-P).
Heat Shock Proteins Do Not Influence Wet Heat Resistance of
Bacillus subtilis
Spores
Authors: Melly Elizabeth , Setlow Peter 
Published: July 2002

ABSTRACT

Spores of
Bacillus subtilis
are significantly more resistant to wet heat than are their vegetative cell counterparts. Analysis of the effects of mutations in and the expression of fusions of a coding gene for a thermostable β-galactosidase to a number of heat shock genes has shown that heat shock proteins play no significant role in the wet heat resistance of
B. subtilis
spores.
Involvement of Two Distinct Catabolite-Responsive Elements in Catabolite Repression of the
Bacillus subtilis myo
-Inositol (
iol
) Operon
Authors: Miwa Yasuhiko , Fujita Yasutaro 
Published: July 2002

ABSTRACT

The
Bacillus subtilis
inositol operon (
iolABCDEFGHIJ
) is involved in
myo
-inositol catabolism. Glucose repression of the
iol
operon induced by inositol is exerted through catabolite repression mediated by CcpA and the
iol
induction system mediated by IolR. In this study, we identified two
iol
catabolite-responsive elements (
cre
's), to which CcpA complexed with P-Ser-HPr or P-Ser-Crh probably binds. One is located in
iolB
(
cre
-
iolB
, nucleotides +2397 to +2411; +1 is the transcription initiation nucleotide), which was the only
cre
-
iol
found in the previous
cre
search of the
B. subtilis
genome using a query sequence of WTGNAANCGNWNNCW (W stands for A or T, and N stands for any base). Deletion and base substitution analysis of the
iol
region indicated that
cre
-
iolB
functions even if it is located far downstream of the
iol
promoter. Further deletion and base substitution analysis revealed another
cre
located between the
iol
promoter and the
iolA
gene (
cre
-i
iolA
, nucleotides +86 to +100); the prefix “i” indicates a location in the intergenic region. Both
cre
-i
iolA
and
cre
-
iolB
appeared to be recognized to almost the same extent by CcpA complexed with either P-Ser-HPr or P-Ser-Crh. Sequence alignment of the six known
cre
's, including
cre
-i
iolA
, which were not revealed in the previous
cre
search, exhibited another consensus sequence of WTGAAARCGYTTWWN (R stands for A or G, and Y stands for C or T); the right two thymines (TT) were found to be essential for the function of
cre
-i
iolA
by means of base substitution analysis. A
cre
search with this query sequence led to the finding of 14 additional putative
cre
's.
Recombination in theompAGene but Not theomcBGene ofChlamydiaContributes to Serovar-Specific Differences in Tissue Tropism, Immune Surveillance, and Persistence of the Organism
Authors: Millman Kim L. , Tavaré Simon , Dean Deborah 
Published: July 2002

ABSTRACTSequences of the major outer membrane protein (MOMP) gene (ompA) and the outer membrane complex B protein gene (omcB) fromChlamydia trachomatis, Chlamydia pneumoniae, andChlamydia psittaciwere analyzed for evidence of intragenic recombination and for linkage equilibrium. The Sawyer runs test, compatibility matrices, and index of association analyses provided substantial evidence that there has been a history of intragenic recombination atompAincluding one instance of interspecies recombination between theC. trachomatismouse pneumonitis strain and theC. pneumoniaehorse N16 strain. Although none of these methods detected intragenic recombination withinomcB, differences in divergence reported in earlier studies suggested that there has been intergenic recombination involvingomcB, and the analyses presented in this study are consistent with this. ForC. trachomatis, index-of-association analyses suggested a higher degree of recombination for C class than for B class strains and a higher degree of recombination in the downstream half ofompA. In concordance with these findings, many significant breakpoints were found in variable segments 3 and 4 of MOMP for the recombinant strains D/B120, G/UW-57, E/Bour, and LGV-98 identified in this study. We provide examples of how genetic diversity generated by repeated recombination in these regions may be associated with evasion of immune surveillance, serovar-specific differences in tissue tropism, and persistence.
Diel Expression of Cell Cycle-Related Genes in Synchronized Cultures of
Prochlorococcus
sp. Strain PCC 9511
Authors: Holtzendorff J. , Partensky F. , Jacquet S. , Bruyant F. , Marie D. , Garczarek L. , Mary I. , Vaulot D. , Hess W. R. 
Published: July 2002

ABSTRACT

The cell cycle of the chlorophyll
b
-possessing marine cyanobacterium
Prochlorococcus
is highly synchronized under natural conditions. To understand the underlying molecular mechanisms we cloned and sequenced
dnaA
and
ftsZ
, two key cell cycle-associated genes, and studied their expression. An axenic culture of
Prochlorococcus
sp. strain PCC 9511 was grown in a turbidostat with a 12 h–12 h light-dark cycle for 2 weeks. During the light periods, a dynamic light regimen was used in order to simulate the natural conditions found in the upper layers of the world's oceans. This treatment resulted in strong cell cycle synchronization that was monitored by flow cytometry. The steady-state mRNA levels of
dnaA
and
ftsZ
were monitored at 4-h intervals during four consecutive division cycles. Both genes exhibited clear diel expression patterns with mRNA maxima during the replication (S) phase. Western blot experiments indicated that the peak of FtsZ concentration occurred at night, i.e., at the time of cell division. Thus, the transcript accumulation of genes involved in replication and division is coordinated in
Prochlorococcus
sp. strain PCC 9511 and might be crucial for determining the timing of DNA replication and cell division.