bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Lipid Core Peptide Construct Containing a Conserved Region Determinant of the Group A Streptococcal M Protein Elicits Heterologous Opsonic Antibodies
Authors: Olive Colleen , Batzloff Michael R. , Horváth Anikó , Wong Allan , Clair Timothy , Yarwood Penny , Toth Istvan , Good Michael F. 
Published: July 2002

ABSTRACTThe study reported here investigated the immunogenicity and protective potential of a lipid core peptide (LCP) construct containing a conserved region determinant of M protein, defined as peptide J8. Parenteral immunization of mice with LCP-J8 led to the induction of high-titer serum immunoglobulin G J8-specific antibodies when the construct was coadministered with complete Freund's adjuvant (CFA) or administered alone. LCP-J8 in CFA had significantly enhanced immunogenicity compared with the monomeric peptide J8 given in CFA. Moreover, LCP-J8/CFA and LCP-J8 antisera opsonized four different group A streptococcal (GAS) strains, and the antisera did not cross-react with human heart tissue proteins. These data indicate the potential of an LCP-based M protein conserved region GAS vaccine in the induction of broadly protective immune responses in the absence of a conventional adjuvant.
Identification of Novel Adhesins from Group B Streptococci by Use of Phage Display Reveals that C5a Peptidase Mediates Fibronectin Binding
Authors: Beckmann Christiane , Waggoner Joshua D. , Harris Theresa O. , Tamura Glen S. , Rubens Craig E. 
Published: July 2002

ABSTRACTGroup B streptococci (GBS) are a major cause of pneumonia, sepsis, and meningitis in newborns and infants. GBS initiate infection of the lung by colonizing mucosal surfaces of the respiratory tract; adherence of the bacteria to host cells is presumed to be the initial step in and prerequisite for successful colonization (G. S. Tamura, J. M. Kuypers, S. Smith, H. Raff, and C. E. Rubens, Infect. Immun. 62:2450-2458, 1994). We have performed a genome-wide screen to identify novel genes of GBS that mediate adherence to fibronectin. A shotgun phage display library was constructed from chromosomal DNA of a serotype Ia GBS strain and affinity selected on immobilized fibronectin. DNA sequence analysis of different clones identified 19 genes with homology to known bacterial adhesin genes, virulence genes, genes involved in transport or metabolic processes, and genes with yet-unknown function. One of the isolated phagemid clones showed significant homology to the gene (scpB) for the GBS C5a peptidase, a surface-associated serine protease that specifically cleaves the complement component C5a, a chemotaxin for polymorphonuclear leukocytes. In this work we have demonstrated that affinity-purified recombinant ScpB and a peptide ScpB fragment (ScpB-PDF), similar to the peptide identified in the phagemid, bound fibronectin in a concentration-dependent manner. Adherence assays to fibronectin were performed, comparing an isogenicscpBmutant to the wild-type strain. Approximately 50% less binding was observed with the mutant than with the wild-type strain. The mutant phenotype could be fully restored by intranscomplementation of the mutant with the cloned wild-typescpBgene, providing further evidence for the role of ScpB in fibronectin adherence. Our results suggest that C5a peptidase is a bifunctional protein, which enzymatically cleaves C5a and mediates adherence to fibronectin. Since binding of fibronectin has been implicated in attachment and invasion of eukaryotic cells by streptococci, our results may imply a second important role for this surface protein in the pathogenesis of GBS infections.
Dissemination of the Phage-Associated Novel Superantigen Gene
speL
in Recent Invasive and Noninvasive
Streptococcus pyogenes
M3/T3 Isolates in Japan
Authors: Ikebe Tadayoshi , Wada Akihito , Inagaki Yoshishige , Sugama Kumiko , Suzuki Rieko , Tanaka Daisuke , Tamaru Aki , Fujinaga Yoshihiro , Abe Yoshiaki , Shimizu Yoshikata , Watanabe Haruo ,   the Working Group for Group A Streptococci in Japan
Published: July 2002

ABSTRACT

In Japan, more than 10% of streptococcal toxic shock-like syndrome (TSLS) cases have been caused by
Streptococcus pyogenes
M3/T3 isolates since the first reported TSLS case in 1992. Most M3/T3 isolates from TSLS or severe invasive infection cases during 1992 to 2001 and those from noninvasive cases during this period are indistinguishable in pulsed-field gel electropherograms. The longest fragments of these recent isolates were 300 kb in size, whereas those of isolates recovered during or before 1973 were 260 kb in size. These 260- and 300-kb fragments hybridized to each other, suggesting the acquisition of an about 40-kb fragment by the recent isolates. The whole part of the acquired fragment was cloned from the first Japanese TSLS isolate, NIH1, and its nucleotide sequence was determined. The 41,796-bp fragment is temperate phage φNIH1.1, containing a new superantigen gene
speL
near its right attachment site. The C-terminal part of the deduced amino acid sequence of
speL
has 48 and 46% similarity with well-characterized erythrogenic toxin SpeC and the most potent superantigen, SmeZ-2, respectively. None of 10 T3 isolates recovered during or before 1973 has
speL
, whereas all of 18 M3/T3 isolates recovered during or after 1992 and, surprisingly,
Streptococcus equi
subsp.
equi
ATCC 9527 do have this gene. Though plaques could not be obtained from φNIH1.1, its DNA became detectable from the phage particle fraction upon mitomycin C induction, showing that this phage is not defective. A horizontal transfer of the phage carrying
speL
may explain the observed change in M3/T3
S. pyogenes
isolates in Japan.
Overproduction of Type 8 Capsular Polysaccharide AugmentsStaphylococcus aureusVirulence
Authors: Luong Thanh T. , Lee Chia Y. 
Published: July 2002

ABSTRACTType 8 capsular polysaccharide (CP8) is the most prevalent capsule type in clinical isolates ofStaphylococcus aureus. However, its role in virulence has not been clearly defined. CP8 strains such as strain Becker produce a small amount of capsule on their surface in vitro. In contrast, CP1 strains such as strain M produce a large amount of capsule, which has been shown to be an important antiphagocytic virulence factor. Thecap8andcap1operons, required for the synthesis of CP8 and CP1, respectively, have been cloned and sequenced. To test whether CP8 contributes to the pathogenesis ofS. aureus, we replaced the weak native promoter of thecap8operon in strain Becker with the strong constitutive promoter of thecap1operon of strain M. The resultant strain, CYL770, synthesizedcap8-specific mRNA at a level about sevenfold higher than that in the parent strain. Remarkably, the CYL770 strain produced about 80-fold more CP8. In a mouse infection model of bacteremia, the CP8-overproducing strain persisted longer in the bloodstream, the liver, and the spleen in mice than the parent strain. In addition, strain CYL770 was more resistant to ospsonophagocytosis in vitro by human polymorphonuclear leukocytes. These results indicate that CP8 is an antiphagocytic virulence factor ofS. aureus.
Contribution of Interleukin-11 and Prostaglandin(s) in Lipopolysaccharide-Induced Bone Resorption In Vivo
Authors: Li Li , Khansari Alireza , Shapira Lior , Graves Dana T. , Amar Salomon 
Published: July 2002

ABSTRACTWe previously demonstrated that interleukin-1 (IL-1) and tumor necrosis factor (TNF) activities only partially account for calvarial bone resorption induced by local application of lipopolysaccharide (LPS) in mice. The present study was undertaken to determine the role and relative contribution of IL-11 and prostaglandin(s) (PG[s]) in LPS-induced bone resorption in vivo. A one-time dose of LPS was injected into the subcutaneous tissue overlying calvaria of mice lacking IL-1 receptor type I (IL-1RI−/−), mice lacking TNF receptor p55 and IL-1RI (TNFRp55−/−-IL-1RI−/−), and wild-type mice. Mice were then treated with injections of anti-IL-11 monoclonal antibody (MAb), indomethacin, or phosphate-buffered saline (PBS) and sacrificed 5 days later. Histological sections stained for tartrate-resistant acid phosphatase (TRAP) were quantified by histomorphometric analysis. At low doses of LPS (100 μg/mouse), the percentages of bone surface covered by osteoclasts were found to be similar in three strains of mice. The increase was reduced by 37% with anti-IL-11 MAb and by 46% with indomethacin. At higher doses of LPS (500 μg/mouse), we found an eightfold increase in these percentages in wild-type mice and a fivefold increase in these percentages in IL-1RI−/−and TNFRp55−/−−IL-1RI−/−mice after normalizing with the value from the saline-PBS control group in the same strain of mice. The increase was reduced by 55 and 69% in wild-type mice and by 50 and 57% in IL-1RI−/−and TNFRp55−/−−IL-1RI−/−mice treated with anti-IL-11 MAb or indomethacin, respectively. Our findings suggest that in vivo, at low doses of LPS (100 μg/mouse), LPS-induced bone resorption is mediated by IL-11 and PGs, while at high doses of LPS (500 μg/mouse), it is mediated by IL-11, PGs, IL-1, and TNF signaling. IL-11 and PGs mediate LPS-induced bone resorption by enhancing osteoclastogenesis independently of the IL-1 or TNF signaling.
Characterization of a
Sinorhizobium meliloti
ATP-Binding Cassette Histidine Transporter Also Involved in Betaine and Proline Uptake
Authors: Boncompagni Eric , Dupont Laurence , Mignot Tam , Østeräs Magne , Lambert Annie , Poggi Marie-Christine , Le Rudulier Daniel 
Published: July 2002

ABSTRACT

The symbiotic soil bacterium
Sinorhizobium meliloti
uses the compatible solutes glycine betaine and proline betaine for both protection against osmotic stress and, at low osmolarities, as an energy source. A PCR strategy based on conserved domains in components of the glycine betaine uptake systems from
Escherichia coli
(ProU) and
Bacillus subtilis
(OpuA and OpuC) allowed us to identify a highly homologous ATP-binding cassette (ABC) binding protein-dependent transporter in
S. meliloti
. This system was encoded by three genes (
hutXWV
) of an operon which also contained a fourth gene (
hutH2
) encoding a putative histidase, which is an enzyme involved in the first step of histidine catabolism. Site-directed mutagenesis of the gene encoding the periplasmic binding protein (
hutX
) and of the gene encoding the cytoplasmic ATPase (
hutV
) was done to study the substrate specificity of this transporter and its contribution in betaine uptake. These mutants showed a 50% reduction in high-affinity uptake of histidine, proline, and proline betaine and about a 30% reduction in low-affinity glycine betaine transport. When histidine was used as a nitrogen source, a 30% inhibition of growth was observed in
hut
mutants (
hutX
and
hutH2
). Expression analysis of the
hut
operon determined using a
hutX-lacZ
fusion revealed induction by histidine, but not by salt stress, suggesting this uptake system has a catabolic role rather than being involved in osmoprotection. To our knowledge, Hut is the first characterized histidine ABC transporter also involved in proline and betaine uptake.
Isolation and Characterization of Canthaxanthin Biosynthesis Genes from the Photosynthetic Bacterium
Bradyrhizobium
sp. Strain ORS278
Authors: Hannibal Laure , Lorquin Jean , D'Ortoli Nicolas Angles , Garcia Nelly , Chaintreuil Clemence , Masson-Boivin Catherine , Dreyfus Bernard , Giraud Eric 
Published: July 2002

ABSTRACT

A carotenoid biosynthesis gene cluster involved in canthaxanthin production was isolated from the photosynthetic
Bradyrhizobium
sp. strain ORS278. This cluster includes five genes identified as
crtE
,
crtY
,
crtI
,
crtB
, and
crtW
that are organized in at least two operons. The functional assignment of each open reading frame was confirmed by complementation studies.
The
Pseudomonas aeruginosa devB/SOL
Homolog,
pgl
, Is a Member of the
hex
Regulon and Encodes 6-Phosphogluconolactonase
Authors: Hager Paul W. , Calfee M. Worth , Phibbs Paul V. 
Published: July 2002

ABSTRACT

A cyclic version of the Entner-Doudoroff pathway is used by
Pseudomonas aeruginosa
to metabolize carbohydrates. Genes encoding the enzymes that catabolize intracellular glucose to pyruvate and glyceraldehyde 3-phosphate are coordinately regulated, clustered at 39 min on the chromosome, and collectively form the
hex
regulon. Within the
hex
cluster is an open reading frame (ORF) with homology to the
devB/SOL
family of unidentified proteins. This ORF encodes a protein of either 243 or 238 amino acids; it overlaps the 5′ end of
zwf
(encodes glucose-6-phosphate dehydrogenase) and is followed immediately by
eda
(encodes the Entner-Doudoroff aldolase). The
devB/SOL
homolog was inactivated in
P. aeruginosa
PAO1 by recombination with a suicide plasmid containing an interrupted copy of the gene, creating mutant strain PAO8029. PAO8029 grows at 9% of the wild-type rate using mannitol as the carbon source and at 50% of the wild-type rate using gluconate as the carbon source. Cell extracts of PAO8029 were specifically deficient in 6-phosphogluconolactonase (Pgl) activity. The cloned
devB/SOL
homolog complemented PAO8029 to restore normal growth on mannitol and gluconate and restored Pgl activity. Hence, we have identified this gene as
pgl
and propose that the
devB/SOL
family members encode 6-phosphogluconolactonases. Interestingly, three eukaryotic glucose-6-phosphate dehydrogenase (G6PDH) isozymes, from human, rabbit, and
Plasmodium falciparum
, contain Pgl domains, suggesting that the sequential reactions of G6PDH and Pgl are incorporated in a single protein. 6-Phosphogluconolactonase activity is induced in
P. aeruginosa
PAO1 by growth on mannitol and repressed by growth on succinate, and it is expressed constitutively in
P. aeruginosa
PAO8026 (
hexR
). Taken together, these results establish that Pgl is an essential enzyme of the cyclic Entner-Doudoroff pathway encoded by
pgl
, a structural gene of the
hex
regulon.
Vibrio cholerae
H-NS Silences Virulence Gene Expression at Multiple Steps in the ToxR Regulatory Cascade
Authors: Nye Melinda B. , Pfau James D. , Skorupski Karen , Taylor Ronald K. 
Published: July 2002

ABSTRACT

H-NS is an abundant nucleoid-associated protein involved in the maintenance of chromosomal architecture in bacteria. H-NS also has a role in silencing the expression of a variety of environmentally regulated genes during growth under nonpermissive conditions. In this study we demonstrate a role for H-NS in the negative modulation of expression of several genes within the ToxR virulence regulon of
Vibrio cholerae
. Deletion of
hns
resulted in high, nearly constitutive levels of expression of the genes encoding cholera toxin, toxin-coregulated pilus, and the ToxT virulence gene regulatory protein. For the cholera toxin- and ToxT-encoding genes, elevated expression in an
hns
mutant was found to occur in the absence of the cognate activator proteins, suggesting that H-NS functions directly at these promoters to decrease gene expression. Deletion analysis of the region upstream of
toxT
suggests that an extensive region located far upstream of the transcriptional start site is required for complete H-NS-mediated repression of gene expression. These data indicate that H-NS negatively influences multiple levels of gene expression within the
V. cholerae
virulence cascade and raise the possibility that the transcriptional activator proteins in the ToxR regulon function to counteract the repressive effects of H-NS at the various promoters as well as to recruit RNA polymerase.
Mutations in Each of thetolGenes ofPseudomonas putidaReveal that They Are Critical for Maintenance of Outer Membrane Stability
Authors: Llamas María A. , Ramos Juan L. , Rodríguez-Herva José J. 
Published: July 2002

ABSTRACTThe outer membrane of gram-negative bacteria functions as a permeability barrier that protects cells against a large number of antibacterial agents. OprL protein ofPseudomonas putidahas been shown to be crucial to maintain the stability of this cell component (J. J. Rodrı́guez-Herva, M.-I. Ramos-González, and J. L. Ramos. J. Bacteriol. 178:1699–1706, 1996). In the present study we cloned and mutagenized theorf1,tolQ,tolR,tolA, andtolBgenes fromP. putidaKT2440, which were located upstream of theoprLgene. Polar and nonpolar mutations of theP. putida tolQ,tolR,tolA, andtolBgenes were generated in vitro by using the Ω-Kmrinterposon, which carries two transcriptional stop signals, or a promoterlessxylEcassette, lacking any transcriptional stop signal, respectively. The mutant constructs were used to inactivate, by reverse genetics procedures, the corresponding chromosomal copies of the genes. The phenotype of each mutant strain was analyzed and compared with those of the wild-type strain and the previously characterizedP. putida oprL::xylEmutant. All mutant strains exhibited a similar phenotype: altered cell morphology, bleb formation at the cell surface, release of periplasmic and outer membrane proteins to the extracellular medium, increased sensitivity to a variety of compounds (i.e., EDTA, sodium dodecyl sulfate, deoxycholate, and some antibiotics), filament formation, and severely reduced cell motility. Altogether, these results demonstrate the importance of the Tol-OprL system for the maintenance of outer membrane integrity inP. putidaand suggest a possible role of these proteins in assembling outer membrane components.
Role of aCandida albicansP1-Type ATPase in Resistance to Copper and Silver Ion Toxicity
Authors: Riggle Perry J. , Kumamoto Carol A. 
Published: July 2002

ABSTRACTCopper ion homeostasis is complicated in that copper is an essential element needed for a variety of cellular processes but is toxic at excess levels. To identifyCandida albicansgenes that are involved in resistance to copper ion toxicity, a library containing inserts ofC. albicansgenomic DNA was used to complement the copper sensitivity phenotype of aSaccharomyces cerevisiae cup1Δ strain that is unable to produce Cup1p, a metallothionein (MT) responsible for high-level copper ion resistance. A P1-type ATPase (CPx type) that is closely related to the human Menkes and Wilson disease proteins was cloned. The gene encoding this pump was termedCRD1(for copper resistance determinant). A gene encoding a 76-amino-acid MT similar to higher eukaryotic MTs in structure was also cloned, and the gene was termedCRD2. Transcription of theCRD1gene was found to increase upon growth with increasing copper levels, while theCRD2mRNA was expressed at a constant level. Strains with theCRD1gene disrupted were extremely sensitive to exogenous copper and failed to grow in medium containing 100 μM CuSO4. Thesecrd1strains also exhibited increased sensitivity to silver and cadmium, indicating that Crd1p is somewhat promiscuous with respect to metal ion transport. Although strains with theCRD2gene disrupted showed reduced growth rate with increasing copper concentration, thecrd2mutants eventually attained wild-type levels of growth, demonstrating thatCRD2is less important for resistance to copper ion toxicity. Crd1p is the first example of a eukaryotic copper pump that provides the primary source of cellular copper resistance, and its ability to confer silver resistance may enhance the prevalence ofC. albicansas a nosocomial pathogen.
The Amino Terminus of
Pseudomonas aeruginosa
Outer Membrane Protein OprF Forms Channels in Lipid Bilayer Membranes: Correlation with a Three-Dimensional Model
Authors: Brinkman Fiona S. L. , Bains Manjeet , Hancock Robert E. W. 
Published: July 2002

ABSTRACT

Pseudomonas aeruginosa
OprF forms 0.36-nS channels and, rarely, 2- to 5-nS channels in lipid bilayer membranes. We show that a protein comprising only the N-terminal 162-amino-acid domain of OprF formed the smaller, but not the larger, channels in lipid bilayers. Circular dichroism spectroscopy indicated that this protein folds into a β-sheet-rich structure, and three-dimensional comparative modeling revealed that it shares significant structural similarity with the amino terminus of the orthologous protein
Escherichia coli
OmpA, which has been shown to form a β-barrel. OprF and OmpA share only 15% identity in this domain, yet these results support the utility of modeling such widely divergent β-barrel domains in three dimensions in order to reveal similarities not readily apparent through primary sequence comparisons. The model is used to further hypothesize why porin activity differs for the N-terminal domains of OprF and OmpA.
Yersinia enterocolitica
ClpB Affects Levels of Invasin and Motility
Authors: Badger Julie L. , Young Briana M. , Darwin Andrew J. , Miller Virginia L. 
Published: July 2002

ABSTRACT

Expression of the
Yersinia enterocolitica inv
gene is dependent on growth phase and temperature.
inv
is maximally expressed at 23°C in late-exponential- to early-stationary-phase cultures. We previously reported the isolation of a
Y. enterocolitica
mutant (JB1A8v) that shows a decrease in invasin levels yet is hypermotile when grown at 23°C. JB1A8v has a transposon insertion within
uvrC
. Described here is the isolation and characterization of a clone that suppresses these mutant phenotypes of the
uvrC
mutant JB1A8v. This suppressing clone encodes ClpB (a Clp ATPase homologue). The
Y. enterocolitica
ClpB homologue is 30 to 40% identical to the ClpB proteins from various bacteria but is 80% identical to one of the two ClpB homologues of
Yersinia pestis
. A
clpB
::Tn
Max2
insertion mutant (JB69Qv) was constructed and determined to be deficient in invasin production and nonmotile when grown at 23°C. Analysis of
inv
and
fleB
(flagellin gene) transcript levels in JB69Qv suggested that ClpB has both transcriptional and posttranscriptional effects. In contrast, a
clpB
null mutant, BY1v, had no effect on invasin levels or motility. A model accounting for these observations is presented.
Maltose and Maltodextrin Transport in the Thermoacidophilic Gram-Positive Bacterium
Alicyclobacillus acidocaldarius
Is Mediated by a High-Affinity Transport System That Includes a Maltose Binding Protein Tolerant to Low pH
Authors: Hülsmann Anja , Lurz Rudi , Scheffel Frank , Schneider Erwin 
Published: July 2002

ABSTRACT

We have studied the uptake of maltose in the thermoacidophilic gram-positive bacterium
Alicyclobacillus acidocaldarius
, which grows best at 57°C and pH 3.5. Under these conditions, accumulation of [
14
C]maltose was observed in cells grown with maltose but not in those grown with glucose. At lower temperatures or higher pH values, the transport rates substantially decreased. Uptake of radiolabeled maltose was inhibited by maltotetraose, acarbose, and cyclodextrins but not by lactose, sucrose, or trehalose. The kinetic parameters (

K
m

of 0.91 ± 0.06 μM and
V
max
ranging from 0.6 to 3.7 nmol/min/mg of protein) are consistent with a binding protein-dependent ATP binding cassette (ABC) transporter. A corresponding binding protein (MalE) that interacts with maltose with high affinity (

K
d

of 1.5 μM) was purified from the culture supernatant of maltose-grown cells. Immunoelectron microscopy revealed distribution of the protein throughout the cell wall. The
malE
gene was cloned and sequenced. Five additional open reading frames, encoding components of a maltose transport system (MalF and MalG), a putative transcriptional regulator (MalR), a cyclodextrinase (CdaA), and an α-glucosidase (GlcA), were identified downstream of
malE
. The
malE
gene lacking the DNA sequence that encodes the signal sequence was expressed in
Escherichia coli
. The purified wild-type and recombinant proteins bind maltose with high affinity over a wide pH range (2.5 to 7) and up to 80°C. Recombinant MalE cross-reacted with an antiserum raised against the wild-type protein, thereby indicating that the latter is the product of the
malE
gene. The MalE protein might be well suited as a model to study tolerance of proteins to low pH.