bluuebunny/crossref_metadata_2025_split huggingface dataset:
S-Nitrosylation of Peroxiredoxin II E Promotes Peroxynitrite-Mediated Tyrosine Nitration
Authors: Romero-Puertas Maria C. , Laxa Miriam , Mattè Alessandro , Zaninotto Federica , Finkemeier Iris , Jones Alex M.E. , Perazzolli Michele , Vandelle Elodie , Dietz Karl-Josef , Delledonne Massimo 
Published: December 2007

AbstractNitric oxide (NO) is a free radical product of cell metabolism that plays diverse and important roles in the regulation of cellular function. S-Nitrosylation is emerging as a specific and fundamental posttranslational protein modification for the transduction of NO bioactivity, but very little is known about its physiological functions in plants. We investigated the molecular mechanism for S-nitrosylation of peroxiredoxin II E (PrxII E) from Arabidopsis thaliana and found that this posttranslational modification inhibits the hydroperoxide-reducing peroxidase activity of PrxII E, thus revealing a novel regulatory mechanism for peroxiredoxins. Furthermore, we obtained biochemical and genetic evidence that PrxII E functions in detoxifying peroxynitrite (ONOO−), a potent oxidizing and nitrating species formed in a diffusion-limited reaction between NO and O2 − that can interfere with Tyr kinase signaling through the nitration of Tyr residues. S-Nitrosylation also inhibits the ONOO− detoxification activity of PrxII E, causing a dramatic increase of ONOO−-dependent nitrotyrosine residue formation. The same increase was observed in a prxII E mutant line after exposure to ONOO−, indicating that the PrxII E modulation of ONOO− bioactivity is biologically relevant. We conclude that NO regulates the effects of its own radicals through the S-nitrosylation of crucial components of the antioxidant defense system that function as common triggers for reactive oxygen species– and NO-mediated signaling events.
Bobel-24 Activity against
Cryptosporidium parvum
in Cell Culture and in a SCID Mouse Model
Authors: Rueda Cristina , Fenoy Soledad , Simón Fernando , del Aguila Carmen 
Published: December 2007

ABSTRACT

The anticryptosporidial activity of Bobel-24 (2,4,6-triiodophenol) was studied for the first time, resulting in a reduction of the in vitro growth of
Cryptosporidium
of up to 99.6%. In a SCID mouse model of chronic cryptosporidiosis, significant differences (
P
< 0.05) in oocyst shedding were observed in animals treated with 125 mg/kg/day. These results merit further investigation of Bobel-24 as a chemotherapeutic option for cryptosporidiosis.
E240V Substitution Increases Catalytic Efficiency toward Ceftazidime in a New Natural TEM-Type Extended-Spectrum β-Lactamase, TEM-149, from
Enterobacter aerogenes
and
Serratia marcescens
Clinical Isolates
Authors: Perilli Mariagrazia , Celenza Giuseppe , De Santis Francesca , Pellegrini Cristina , Forcella Chiara , Rossolini Gian Maria , Stefani Stefania , Amicosante Gianfranco 
Published: December 2007

ABSTRACT

The aim of this study was to characterize a novel extended-spectrum β-lactamase that belongs to the TEM family, the TEM-149 enzyme, and that was isolated from the urine of two hospitalized patients from different hospitals in southern Italy. The peculiarity of this enzyme was the finding of a valine residue at position 240. The array of amino acid substitutions found in TEM-149 was as follows: E104K, R164S, M182T, and E240V. A reversion of a threonine residue at position 182 was also performed to create a new mutant, TEM-149
T182M
, in order to assess the contribution of this substitution on the kinetic profile and the stability of TEM-149. The
bla
TEM-149
and
bla
TEM-149/T182M
genes were cloned into pBC-SK, and the corresponding enzymes were purified from recombinant
Escherichia coli
HB101 by the same procedure. Both enzymes hydrolyzed all β-lactams tested, with a preference for ceftazidime, which was found to be the best substrate. By comparison of the kinetic parameters of the TEM-149 and the TEM-149
T182M
enzymes, a reduction of the catalytic efficiency for the TEM-149
T182M
mutant was observed against all substrates tested except benzylpenicillin, cefotaxime, and aztreonam. Tazobactam, clavulanic acid, and sulbactam were good inhibitors of the TEM-149 β-lactamase.
Effects ofEscherichia coliLipopolysaccharide on Telithromycin Pharmacokinetics in Rats: Inhibition of Metabolism via CYP3A
Authors: Lee Joo H. , Cho Yu K. , Jung Young S. , Kim Young C. , Lee Myung G. 
Published: December 2007

ABSTRACTIt has been reported that telithromycin is metabolized primarily via hepatic microsomal cytochrome P450 (CYP) 3A1/2 in rats and that the expression of hepatic and intestinal CYP3A decreases in rats pretreated withEscherichia colilipopolysaccharide (ECLPS rats; an animal model of inflammation). Thus, it is possible that the area under the plasma concentration-time curve from 0 h to infinity (AUC0-∞) of intravenous and oral telithromycin is greater for ECLPS rats than for the controls. To assess this, the pharmacokinetic parameters of telithromycin were compared after intravenous and oral administration (50 mg/kg). After intravenous administration of telithromycin, the AUC0-∞was significantly greater (by 83.4%) in ECLPS rats due to a significantly lower nonrenal clearance (by 44.5%) than in the controls. This may have been due to a significantly decreased hepatic metabolism of telithromycin in ECLPS rats. After oral administration of telithromycin, the AUC0-∞in ECLPS rats was also significantly greater (by 140%) than in the controls and the increase was considerably greater than the 83.4% increase after intravenous administration. This could have been due to a decrease in intestinal metabolism in addition to a decreased hepatic metabolism of telithromycin in ECLPS rats.
Protozoan Migration in Bent Microfluidic Channels
Authors: Wang Wei , Shor Leslie M. , LeBoeuf Eugene J. , Wikswo John P. , Taghon Gary L. , Kosson David S. 
Published: December 2007

ABSTRACT
Microfluidic devices permit direct observation of microbial behavior in defined microstructured settings. Here, the swimming speed and dispersal of individual marine ciliates in straight and bent microfluidic channels were quantified. The dispersal rate and swimming speed increased with channel width, decreased with protozoan size, and was significantly impacted by the channel turning angle.
Direct Identification of a Bacterial Manganese(II) Oxidase, the Multicopper Oxidase MnxG, from Spores of Several Different Marine
Bacillus
Species
Authors: Dick Gregory J. , Torpey Justin W. , Beveridge Terry J. , Tebo Bradley M. 
Published: December 2007

ABSTRACT

Microorganisms catalyze the formation of naturally occurring Mn oxides, but little is known about the biochemical mechanisms of this important biogeochemical process. We used tandem mass spectrometry to directly analyze the Mn(II)-oxidizing enzyme from marine
Bacillus
spores, identified as an Mn oxide band with an in-gel activity assay. Nine distinct peptides recovered from the Mn oxide band of two
Bacillus
species were unique to the multicopper oxidase MnxG, and one peptide was from the small hydrophobic protein MnxF. No other proteins were detected in the Mn oxide band, indicating that MnxG (or a MnxF/G complex) directly catalyzes biogenic Mn oxide formation. The Mn(II) oxidase was partially purified and found to be resistant to many proteases and active even at high concentrations of sodium dodecyl sulfate. Comparative analysis of the genes involved in Mn(II) oxidation from three diverse
Bacillus
species revealed a complement of conserved Cu-binding regions not present in well-characterized multicopper oxidases. Our results provide the first direct identification of a bacterial enzyme that catalyzes Mn(II) oxidation and suggest that MnxG catalyzes two sequential one-electron oxidations from Mn(II) to Mn(III) and from Mn(III) to Mn(IV), a novel type of reaction for a multicopper oxidase.
Applicability of Phylogenetic Methods for Characterizing the Public Health Significance of Verocytotoxin-Producing
Escherichia coli
Strains
Authors: Ziebell Kim , Konczy Paulina , Yong Irene , Frost Shelley , Mascarenhas Mariola , Kropinski Andrew M. , Whittam Thomas S. , Read Susan C. , Karmali Mohamed A. 
Published: December 2007

ABSTRACT

Two phylogenetic methods (multilocus sequence typing [MLST] and a multiplex PCR) were investigated to determine whether phylogenetic classification of verocytotoxin-producing
Escherichia coli
serotypes correlates with their classification into groups (seropathotypes A to E) based on their relative incidence in human disease and on their association with outbreaks and serious complications. MLST was able to separate 96% of seropathotype D and E serotypes from those that cause serious disease (seropathotypes A to C), whereas the multiplex PCR lacked this level of seropathotype discrimination.
cadDX
Operon of
Streptococcus salivarius
57.I
Authors: Chen Yi-Ywan M. , Feng C. W. , Chiu C. F. , Burne Robert A. 
Published: December 2007

ABSTRACT

A CadDX system that confers resistance to Cd
2+
and Zn
2+
was identified in
Streptococcus salivarius
57.I. Unlike with other CadDX systems, the expression of the
cad
promoter was negatively regulated by CadX, and the repression was inducible by Cd
2+
and Zn
2+
, similar to what was found for CadCA systems. The lower G+C content of the
S. salivarius cadDX
genes suggests acquisition by horizontal gene transfer.
Retrospective Study of
Campylobacter
Infection in a Zoological Collection
Authors: Taema Maged M. , Bull James C. , Macgregor Shaheed K. , Flach Edmund J. , Boardman Wayne S. , Routh Andrew D. 
Published: December 2007

ABSTRACT

Little is known about the epidemiology of
Campylobacter
spp. in wild animal populations. However, zoological collections can provide valuable insights. Using records from the Zoological Society of London Whipsnade Zoo compiled between 1990 and 2003, the roles of a range of biotic and abiotic factors associated with the occurrence of campylobacteriosis were investigated. The occurrence of campylobacteriosis varied widely across host taxonomic orders. Furthermore, in mammals, a combination of changes in both rainfall and temperature in the week preceding the onset of gastroenteritis were associated with isolation of
Campylobacter
from feces. In birds, there was a weak negative correlation between mean weekly rainfall and isolation of
Campylobacter
from feces. Importantly, in birds we found that the mean weekly rainfall 3 to 4 weeks before symptoms of gastroenteritis appeared was the best predictor of
Campylobacter
infection.
Campylobacter
-related gastroenteritis cases with mixed concurrent infections were positively associated with the presence of parasites (helminths and protozoans) in mammals, while in birds
Campylobacter
was associated with other concurrent bacterial infections rather than with the presence of helminths and protozoans. This study suggests that climatic elements are important factors associated with
Campylobacter
-related gastroenteritis. Further investigations are required to improve our understanding of
Campylobacter
epidemiology in captive wild animal populations.
Bacterial Cinnamoyl Esterase Activity Screening for the Production of a Novel Functional Food Product
Authors: Guglielmetti Simone , De Noni Ivano , Caracciolo Federica , Molinari Francesco , Parini Carlo , Mora Diego 
Published: December 2007

ABSTRACT

Lactobacillus helveticus
MIMLh5 was selected for its strong cinnamoyl esterase activity on chlorogenic acid and employed for the preparation of a food product containing a high concentration of free caffeic acid. The novel food product was demonstrated to display high total antioxidant power and potential probiotic properties.
Mitochondrial
cob
and
cox1
Genes and Editing of the Corresponding mRNAs in
Dinophysis acuminata
from Narragansett Bay, with Special Reference to the Phylogenetic Position of the Genus
Dinophysis
Authors: Zhang Huan , Bhattacharya Debashish , Maranda Lucie , Lin Senjie 
Published: December 2007

ABSTRACT

Dinophysis acuminata
cells were isolated from Narragansett Bay water samples in June 2005 using flow cytometry. Dinoflagellate-specific PCR primers were used to isolate small-subunit rRNA (18S rRNA), mitochondrial cytochrome
b
(
cob
), and cytochrome
c
oxidase I (
cox1
) genes and the encoded cDNAs. Maximum-likelihood analysis of a concatenated data set of ribosomal DNA and cDNA sequences of
cob
and
cox1
showed that
D. acuminata
was sister to Gonyaulacoids, but without strong bootstrap support. The approximately unbiased test could not reject alternative positions of
D. acuminata
. To gain better resolution, mRNA editing of
cob
and
cox1
was inferred for
D. acuminata
and 13 other dinoflagellate species. The location and type of editing as well as the distribution pattern in
D. acuminata
were generally similar to those in other dinoflagellates except for two edited sites that are unique to this species. Bayesian analyses of a matrix that recorded the location and type of editing, and of a matrix that included the protein sequences of COB and COX1 with the editing data yielded tree topologies similar to the three-gene tree but again failed to resolve the phylogenetic position of
D. acuminata
. However, the density of edited sites in the
D. acuminata
mitochondrial genes, consistent with phylogenetic trees, indicated that
Dinophysis
is a derived dinoflagellate lineage, diverging after other lineages such as
Oxyrrhis
,
Amphidinium
, and
Symbiodinium
. We demonstrate that dinoflagellate-specific PCR coupled with flow cytometry can be a useful tool to analyze genes and their transcripts from a natural dinoflagellate population.
Detection of Plant-Modulated Alterations in Antifungal Gene Expression in
Pseudomonas fluorescens
CHA0 on Roots by Flow Cytometry
Authors: de Werra Patrice , Baehler Eric , Huser Aurélie , Keel Christoph , Maurhofer Monika 
Published: December 2007

ABSTRACT

The biocontrol activity of the root-colonizing
Pseudomonas fluorescens
strain CHA0 is largely determined by the production of antifungal metabolites, especially 2,4-diacetylphloroglucinol. The expression of these metabolites depends on abiotic and biotic environmental factors, in particular, elements present in the rhizosphere. In this study, we have developed a new method for the in situ analysis of antifungal gene expression using flow cytometry combined with green fluorescent protein (GFP)-based reporter fusions to the
phlA
and
prnA
genes essential for the production of the antifungal compounds 2,4-diacetylphloroglucinol and pyrrolnitrin, respectively, in strain CHA0. Expression of
phlA
-
gfp
and
prnA
-
gfp
in CHA0 cells harvested from the rhizosphere of a set of plant species as well as from the roots of healthy, leaf pathogen-attacked, and physically stressed plants were analyzed using a FACSCalibur. After subtraction of background fluorescence emitted by plant-derived particles and CHA0 cells not carrying the
gfp
reporters, the average gene expression per bacterial cell could be calculated. Levels of
phlA
and
prnA
expression varied significantly in the rhizospheres of different plant species. Physical stress and leaf pathogen infection lowered
phlA
expression levels in the rhizosphere of cucumber. Our results demonstrate that the newly developed approach is suitable to monitor differences in levels of antifungal gene expression in response to various plant-derived factors. An advantage of the method is that it allows quantification of bacterial gene expression in rhizosphere populations at a single-cell level. To our best knowledge, this is the first study using flow cytometry for the in situ analysis of biocontrol gene expression in a plant-beneficial bacterium in the rhizosphere.
Strategy for In Situ Detection of Natural Transformation-Based Horizontal Gene Transfer Events
Authors: Rizzi Aurora , Pontiroli Alessandra , Brusetti Lorenzo , Borin Sara , Sorlini Claudia , Abruzzese Alessandro , Sacchi Gian Attilio , Vogel Timothy M. , Simonet Pascal , Bazzicalupo Marco , Nielsen Kaare Magne , Monier Jean-Michel , Daffonchio Daniele 
Published: December 2007

ABSTRACT

A strategy is described that enables the in situ detection of natural transformation in
Acinetobacter baylyi
BD413 by the expression of a green fluorescent protein. Microscale detection of bacterial transformants growing on plant tissues was shown by fluorescence microscopy and indicated that cultivation-based selection of transformants on antibiotic-containing agar plates underestimates transformation frequencies.
Factors and Selenocysteine Insertion Sequence Requirements for the Synthesis of Selenoproteins from a Gram-Positive Anaerobe in
Escherichia coli
Authors: Gursinsky Torsten , Gröbe Daniel , Schierhorn Angelika , Jäger Jana , Andreesen Jan R. , Söhling Brigitte 
Published: December 2007

ABSTRACT

Selenoprotein synthesis in
Escherichia coli
strictly depends on the presence of a specific selenocysteine insertion sequence (SECIS) following the selenocysteine-encoding UGA codon of the respective mRNA. It is recognized by the selenocysteine-specific elongation factor SelB, leading to cotranslational insertion of selenocysteine into the nascent polypeptide chain. The synthesis of three different selenoproteins from the gram-positive anaerobe
Eubacterium acidaminophilum
in
E. coli
was studied. Incorporation of
75
Se into glycine reductase protein B (GrdB1), the peroxiredoxin PrxU, and selenophosphate synthetase (SelD1) was negligible in an
E. coli
wild-type strain and was fully absent in an
E. coli
SelB mutant. Selenoprotein synthesis, however, was strongly increased if
selB
and
selC
(tRNA
Sec
) from
E. acidaminophilum
were coexpressed. Putative secondary structures downstream of the UGA codons did not show any sequence similarity to each other or to the
E. coli
SECIS element. However, mutations in these structures strongly reduced the amount of
75
Se-labeled protein, indicating that they indeed act as SECIS elements. UGA readthrough mediated by the three different SECIS elements was further analyzed using
gst-lacZ
translational fusions. In the presence of
selB
and
selC
from
E. acidaminophilum
, UGA readthrough was 36 to 64% compared to the respective cysteine-encoding UGC variant. UGA readthrough of SECIS elements present in
Desulfomicrobium baculatum
(
hydV
),
Treponema denticola
(
selD
), and
Campylobacter jejuni
(
selW
-like gene) was also considerably enhanced in the presence of
E. acidaminophilum selB
and
selC.
This indicates recognition of these SECIS elements and might open new perspectives for heterologous selenoprotein synthesis in
E. coli
.
Genetic Rearrangement Strategy for Optimizing the Dibenzothiophene Biodesulfurization Pathway in
Rhodococcus erythropolis
Authors: Li Guo-qiang , Li Shan-shan , Zhang Ming-lu , Wang Jun , Zhu Lin , Liang Feng-lai , Liu Ru-lin , Ma Ting 
Published: December 2007

ABSTRACT

Dibenzothiophene (DBT) and its derivatives can be microbially desulfurized by enzymes DszC, DszA, and DszB, which are encoded by the operon
dszABC
and contribute to the conversion in tandem. We investigated the expression characteristics of the
dsz
operon. Our results revealed that the levels of transcription and translation of
dszA
,
dszB
, and
dszC
decreased according to the positions of the genes in the
dsz
operon. Furthermore, the translation of
dszB
was repressed by an overlapping structure in the
dsz
operon. In order to get better and steady expression of the Dsz enzymes and optimize the metabolic flux of DBT, we rearranged the
dsz
operon according to the catalytic capabilities of the Dsz enzymes and expressed the rearranged
dsz
operon,
dszBCA
, in
Rhodococcus erythropolis
. After rearrangement, the ratio of
dszA
,
dszB
, and
dszC
mRNAs in the cells was changed, from 11:3.3:1 to 1:16:5. Western blot analysis revealed that the levels of expression of
dszB
and
dszC
had been enhanced but that the expression of
dszA
had decreased. The desulfurization activity of resting cells prepared from
R. erythropolis
DRB, which carried the rearranged
dsz
operon, was about 12-fold higher than that of resting cells of
R. erythropolis
DRA, which carried the original operon in a similarly constructed vector.
Marker Removal in Staphylococci via Cre Recombinase and Different
lox
Sites
Authors: Leibig Martina , Krismer Bernhard , Kolb Martina , Friede Alexandra , Götz Friedrich , Bertram Ralph 
Published: December 2007

ABSTRACT

Allelic replacement in staphylococci is frequently aided by antibiotic resistance markers that replace the gene(s) of interest. In multiply modified strains, the number of mutated genes usually correlates with the number of selection markers in the strain's chromosome. Site-specific recombination systems are capable of eliminating such markers, if they are flanked by recombinase recognition sites. In this study, a Cre-
lox
setting was established that allowed the efficient removal of resistance genes from the genomes of
Staphylococcus carnosus
and
S. aureus
. Two cassettes conferring resistance to erythromycin or kanamycin were flanked with wild-type or mutant
lox
sites, respectively, and used to delete single genes and an entire operon. After transformation of the cells with a newly constructed
cre
expression plasmid (pRAB1), genomic eviction of the resistance genes was observed in approximately one out of ten candidates analyzed and subsequently verified by PCR. Due to its thermosensitive origin of replication, the plasmid was then easily eliminated at nonpermissive temperatures. We anticipate that the system presented here will prove useful for generating markerless deletion mutants in staphylococci.
A
Legionella pneumophila
Peptidyl-Prolyl
cis
-
trans
Isomerase Present in Culture Supernatants Is Necessary for Optimal Growth at Low Temperatures
Authors: Söderberg Maria A. , Cianciotto Nicholas P. 
Published: December 2007

ABSTRACT

Several
Legionella pneumophila
proteins were highly expressed in low-temperature supernatants. One of these proteins was the peptidyl-prolyl isomerase PpiB. Mutants lacking
ppiB
exhibited reduced growth at 17°C. Since PpiB lacked a signal sequence and was present in 17°C supernatants of type II and type IV secretion mutants, this protein may be secreted by a novel mechanism.
The
Escherichia coli
Efflux Pump TolC Promotes Aggregation of Enteroaggregative
E. coli
042
Authors: Imuta Naoko , Nishi Junichiro , Tokuda Koichi , Fujiyama Rika , Manago Kunihiro , Iwashita Mayumi , Sarantuya Jav , Kawano Yoshifumi 
Published: December 2007

ABSTRACT

Enteroaggregative
Escherichia coli
(EAEC) is an emerging enteric pathogen in both developing and industrialized countries. EAEC is defined as a diarrheal pathogen based on its characteristic aggregative adherence to HEp-2 cells in culture and its biofilm formation on the intestinal mucosa. We have reported that the novel protein AatA, which is encoded on the EAEC virulence plasmid pAA2, localizes to the outer membrane and facilitates export of the dispersin Aap across the outer membrane. Because AatA is an
E. coli
efflux pump TolC homolog, we investigated the role of TolC in the virulence of EAEC. No difference in Aap secretion was observed between the wild type and its
tolC
mutant (042
tolC
). However, characteristic aggregation in high-glucose Dulbecco's minimal essential medium for the wild type was diminished for 042
tolC
. In a microtiter plate assay, there were significantly more planktonic cells for 042
tolC
than for the wild type, while there were significantly fewer spontaneously precipitated cells on the substratum for 042
tolC
than for the wild type. In a HEp-2 cell adherence test, 042
tolC
showed less aggregative adherence than did the wild type. The strong aggregation and aggregative adherence were restored in the complement strain with
tolC
. In a transwell assay, planktonic cells of 042
tolC
decreased when cocultured with the wild type or the complement, while precipitated cells of 042
tolC
increased when cocultured with them. These results suggest that TolC promotes the aggregation and adhesion of EAEC 042 by secreting an assumed humoral factor.