bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic Evidence Identifying the True Gluconeogenic Fructose-1,6-Bisphosphatase in
Thermococcus kodakaraensis
and Other Hyperthermophiles
Authors: Sato Takaaki , Imanaka Hiroyuki , Rashid Naeem , Fukui Toshiaki , Atomi Haruyuki , Imanaka Tadayuki 
Published: August 2004

ABSTRACT

Fructose-1,6-bisphosphatase (FBPase) is one of the key enzymes in gluconeogenesis. Although FBPase activity has been detected in several hyperthermophiles, no orthologs corresponding to the classical FBPases from bacteria and eukaryotes have been identified in their genomes. An inositol monophosphatase (IMPase) from
Methanococcus jannaschii
which displayed both FBPase and IMPase activities and a structurally novel FBPase (Fbp

Tk

) from the hyperthermophilic archaeon
Thermococcus kodakaraensis
KOD1 have been proposed as the “missing” FBPase. For this study, using
T. kodakaraensis
, we took a genetic approach to elucidate which candidate is the major gluconeogenic enzyme in vivo. The IMPase/FBPase ortholog in
T. kodakaraensis
, Imp

Tk

, was confirmed to possess high FBPase activity along with IMPase activity, as in the case of other orthologs. We therefore constructed Δ
fbp
and Δ
imp
strains by applying a gene disruption system recently developed for
T. kodakaraensis
and investigated their phenotypes. The Δ
fbp
strain could not grow under gluconeogenic conditions while glycolytic growth was unimpaired, and the disruption resulted in the complete abolishment of intracellular FBPase activity. Evidently,

fbp
Tk

is an indispensable gene for gluconeogenesis and is responsible for almost all intracellular FBPase activity. In contrast, the endogenous

imp
Tk

gene could not complement the defect of the
fbp
deletion, and its disruption did not lead to any detectable phenotypic changes under the conditions examined. These facts indicated that

imp
Tk

is irrelevant to gluconeogenesis, despite the high FBPase activity of its protein product, probably due to insufficient transcription. Our results provide strong evidence that the true FBPase for gluconeogenesis in
T. kodakaraensis
is the Fbp

Tk

ortholog, not the IMPase/FBPase ortholog.
Thermus thermophilus
L11 Methyltransferase, PrmA, Is Dispensable for Growth and Preferentially Modifies Free Ribosomal Protein L11 Prior to Ribosome Assembly
Authors: Cameron Dale M. , Gregory Steven T. , Thompson Jill , Suh Moo-Jin , Limbach Patrick A. , Dahlberg Albert E. 
Published: August 2004

ABSTRACT

The ribosomal protein L11 in bacteria is posttranslationally trimethylated at multiple amino acid positions by the L11 methyltransferase PrmA, the product of the
prmA
gene. The role of L11 methylation in ribosome function or assembly has yet to be determined, although the deletion of
Escherichia coli prmA
has no apparent phenotype. We have constructed a mutant of the extreme thermophile
Thermus thermophilus
in which the
prmA
gene has been disrupted with the
htk
gene encoding a heat-stable kanamycin adenyltransferase. This mutant shows no growth defects, indicating that
T. thermophilus
PrmA, like its
E. coli
homolog, is dispensable. Ribosomes prepared from this mutant contain unmethylated L11, as determined by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and are effective substrates for in vitro methylation by cloned and purified
T. thermophilus
PrmA. MALDI-TOF MS also revealed that
T. thermophilus
L11 contains a total of 12 methyl groups, in contrast to the 9 methyl groups found in
E. coli
L11. Finally, we found that, as with the
E. coli
methyltransferase, the ribosomal protein L11 dissociated from ribosomes is a more efficient substrate for in vitro methylation by PrmA than intact 70S ribosomes, suggesting that methylation in vivo occurs on free L11 prior to its incorporation into ribosomes.
Linkage between Catecholate Siderophores and the Multicopper Oxidase CueO in
Escherichia coli
Authors: Grass Gregor , Thakali Keshari , Klebba Phillip E. , Thieme Daniel , Müller Axel , Wildner Günter F. , Rensing Christopher 
Published: August 2004

ABSTRACT

The multicopper oxidase CueO had previously been demonstrated to exhibit phenoloxidase activity and was implicated in intrinsic copper resistance in
Escherichia coli
. Catecholates can potentially reduce Cu(II) to the prooxidant Cu(I). In this report we provide evidence that CueO protects
E. coli
cells by oxidizing enterobactin, the catechol iron siderophore of
E. coli
, in the presence of copper. In vitro, a mixture of enterobactin and copper was toxic for
E. coli
cells, but the addition of purified CueO led to their survival. Deletion of
fur
resulted in copper hypersensitivity that was alleviated by additional deletion of
entC
, preventing synthesis of enterobactin. In addition, copper added together with 2,3-dihydroxybenzoic acid or enterobactin was able to induce a Φ(
cueO-lacZ
) operon fusion more efficiently than copper alone. The reaction product of the 2,3-dihydroxybenzoic acid oxidation by CueO that can complex Cu(II) ions was determined by gas chromatography-mass spectroscopy and identified as 2-carboxymuconate.
A Novel Sortase, SrtC2, from
Streptococcus pyogenes
Anchors a Surface Protein Containing a QVPTGV Motif to the Cell Wall
Authors: Barnett Timothy C. , Patel Aman R. , Scott June R. 
Published: August 2004

ABSTRACT

The important human pathogen
Streptococcus pyogenes
(group A streptococcus GAS), requires several surface proteins to interact with its human host. Many of these are covalently linked by a sortase enzyme to the cell wall via a C-terminal LPXTG motif. This motif is followed by a hydrophobic region and charged C terminus, which are thought to retard the protein in the cell membrane to facilitate recognition by the membrane-localized sortase. Previously, we identified two sortase enzymes in GAS. SrtA is found in all GAS strains and anchors most proteins containing LPXTG, while SrtB is present only in some strains and anchors a subset of LPXTG-containing proteins. We now report the presence of a third sortase in most strains of GAS, SrtC. We show that SrtC mediates attachment of a protein with a QVPTGV motif preceding a hydrophobic region and charged tail. We also demonstrate that the QVPTGV sequence is a substrate for anchoring of this protein by SrtC. Furthermore, replacing this motif with LPSTGE, found in the SrtA-anchored M protein of GAS, leads to SrtA-dependent secretion of the protein but does not lead to its anchoring by SrtA. We conclude that
srtC
encodes a novel sortase that anchors a protein containing a QVPTGV motif to the surface of GAS.
Characterization of
Salmonella enterica
Subspecies I Genovars by Use of Microarrays
Authors: Porwollik S. , Boyd E. F. , Choy C. , Cheng P. , Florea L. , Proctor E. , McClelland M. 
Published: August 2004

ABSTRACT

Subspecies 1 of
Salmonella enterica
is responsible for almost all
Salmonella
infections of warm-blooded animals. Within subspecies 1 there are over 2,300 known serovars that differ in their prevalence and the diseases that they cause in different hosts. Only a few of these serovars are responsible for most
Salmonella
infections in humans and domestic animals. The gene contents of 79 strains from the most prevalent serovars were profiled by microarray analysis. Strains within the same serovar often differed by the presence and absence of hundreds of genes. Gene contents sometimes differed more within a serovar than between serovars. Groups of strains that share a distinct profile of gene content can be referred to as “genovars” to distinguish them from serovars. Several misassignments within the
Salmonella
reference B collection were detected by genovar typing and were subsequently confirmed serologically. Just as serology has proved useful for understanding the host range and pathogenic manifestations of
Salmonella
, genovars are likely to further define previously unrecognized specific features of
Salmonella
infections.
High-Resolution Structure of the Histidine-Containing Phosphocarrier Protein (HPr) fromStaphylococcus aureusand Characterization of Its Interaction with the Bifunctional HPr Kinase/Phosphorylase
Authors: Maurer Till , Meier Sebastian , Kachel Norman , Munte Claudia Elisabeth , Hasenbein Sonja , Koch Brigitte , Hengstenberg Wolfgang , Kalbitzer Hans Robert 
Published: August 2004

ABSTRACTA high-resolution structure of the histidine-containing phosphocarrier protein (HPr) fromStaphylococcus aureuswas obtained by heteronuclear multidimensional nuclear magnetic resonance (NMR) spectroscopy on the basis of 1,766 structural restraints. Twenty-three hydrogen bonds in HPr could be directly detected by polarization transfer from the amide nitrogen to the carbonyl carbon involved in the hydrogen bond. Differential line broadening was used to characterize the interaction of HPr with the HPr kinase/phosphorylase (HPrK/P) ofStaphylococcus xylosus, which is responsible for phosphorylation-dephosphorylation of the hydroxyl group of the regulatory serine residue at position 46. The dissociation constantKdwas determined to be 0.10 ± 0.02 mM at 303 K from the NMR data, assuming independent binding. The data are consistent with a stoichiometry of 1 HPr molecule per HPrK/P monomer in solution. Using transversal relaxation optimized spectroscopy-heteronuclear single quantum correlation, we mapped the interaction site of the two proteins in the 330-kDa complex. As expected, it covers the region around Ser46 and the small helix b following this residue. In addition, HPrK/P also binds to the second phosphorylation site of HPr at position 15. This interaction may be essential for the recognition of the phosphorylation state of His15 and the phosphorylation-dependent regulation of the kinase/phosphorylase activity. In accordance with this observation, the recently published X-ray structure of the HPr/HPrK core protein complex fromLactobacillus caseishows interactions with the two phosphorylation sites. However, the NMR data also suggest differences for the full-length protein fromS. xylosus: there are no indications for an interaction with the residues preceding the regulatory Ser46 residue (Thr41 to Lys45) in the protein ofS. xylosus. In contrast, it seems to interact with the C-terminal helix of HPr in solution, an interaction which is not observed for the complex of HPr with the core of HPrK/P ofL. caseiin crystals.
Substrate Specificity of the
Escherichia coli
Outer Membrane Protease OmpT
Authors: McCarter John D. , Stephens Daren , Shoemaker Kevin , Rosenberg Steve , Kirsch Jack F. , Georgiou George 
Published: August 2004

ABSTRACT

OmpT is a surface protease of gram-negative bacteria that has been shown to cleave antimicrobial peptides, activate human plasminogen, and degrade some recombinant heterologous proteins. We have analyzed the substrate specificity of OmpT by two complementary substrate filamentous phage display methods: (i) in situ cleavage of phage that display protease-susceptible peptides by
Escherichia coli
expressing OmpT and (ii) in vitro cleavage of phage-displayed peptides using purified enzyme. Consistent with previous reports, OmpT was found to exhibit a virtual requirement for Arg in the P1 position and a slightly less stringent preference for this residue in the P1′ position (P1 and P1′ are the residues immediately prior to and following the scissile bond). Lys, Gly, and Val were also found in the P1′ position. The most common residues in the P2′ position were Val or Ala, and the P3 and P4 positions exhibited a preference for Trp or Arg. Synthetic peptides based upon sequences selected by bacteriophage display were cleaved very efficiently, with
k
cat
/
K

m

values up to 7.3 × 10
6
M
−1
s
−1
. In contrast, a peptide corresponding to the cleavage site of human plasminogen was hydrolyzed with a
k
cat
/
K

m

almost 10
6
-fold lower. Overall, the results presented in this work indicate that in addition to the P1 and P1′ positions, additional amino acids within a six-residue window (between P4 and P2′) contribute to the binding of substrate polypeptides to the OmpT binding site.
Transcription Regulation ofezrAand Its Effect on Cell Division ofBacillus subtilis
Authors: Chung Kuei-Min , Hsu Hsin-Hsien , Govindan Suresh , Chang Ban-Yang 
Published: August 2004

ABSTRACTThe EzrA protein ofBacillus subtilisis a negative regulator for FtsZ (Z)-ring formation. It is able to modulate the frequency and position of Z-ring formation during cell division. The loss of this protein results in cells with multiple Z rings located at polar as well as medial sites; it also lowers the critical concentration of FtsZ required for ring formation (P. A. Levin, I. G. Kurster, and A. D. Grossman, Proc. Natl. Acad. Sci. USA96:9642-9647, 1999). We have studied the regulation ofezrAexpression during the growth ofB. subtilisand its effects on the intracellular level of EzrA as well as the cell length ofB. subtilis. With the aid of promoter probing, primer extension, in vitro transcription, and Western blotting analyses, two overlapping σA-type promoters, P1 and P2, located about 100 bp upstream of the initiation codon ofezrA, have been identified. P1, supposed to be an extended −10 promoter, was responsible for most of theezrAexpression during the growth ofB. subtilis. Disruption of this promoter reduced the intracellular level of EzrA very significantly compared with disruption of P2. Moreover, deletion of both promoters completely abolished EzrA inB. subtilis. More importantly, the cell length and percentage of filamentous cells ofB. subtiliswere significantly increased by disruption of the promoter(s). Thus, EzrA is required for efficient cell division during the growth ofB. subtilis, despite serving as a negative regulator for Z-ring formation.
FlhF, the Third Signal Recognition Particle-GTPase of
Bacillus subtilis
, Is Dispensable for Protein Secretion
Authors: Zanen Geeske , Antelmann Haike , Westers Helga , Hecker Michael , van Dijl Jan Maarten , Quax Wim J. 
Published: August 2004

ABSTRACT

Bacillus subtilis
contains three proteins of the signal recognition particle-GTPase family known as Ffh, FtsY, and FlhF. Here we show that FlhF is dispensable for protein secretion, unlike Ffh and FtsY. Although
flhF
is located in the
fla
/
che
operon,
B. subtilis
168
flhF
mutant cells assemble flagella and are motile.
Overexpression of
gnsA
, a Multicopy Suppressor of the
secG
Null Mutation, Increases Acidic Phospholipid Contents by Inhibiting Phosphatidylethanolamine Synthesis at Low Temperatures
Authors: Sugai Rie , Shimizu Hisayo , Nishiyama Ken-ichi , Tokuda Hajime 
Published: August 2004

ABSTRACT

GnsA overproduction was previously found to suppress both the
secG
null mutation and the
fabA6
mutation in
Escherichia coli
by increasing the unsaturated fatty acid contents. We report here that it also increased the acidic phospholipid contents at 20°C but not at 37°C. GnsA overproduction at 20°C specifically inhibited phosphatidylethanolamine synthesis and therefore caused the increase in the proportion of acidic phospholipids.
Burnout and work environments of public health nurses involved in mental health care
Authors: Imai H , Nakao H , Tsuchiya M , Kuroda Y , Katoh T 
Published: August 2004

Aims:(1) To examine whether prevalence of burnout is higher among community psychiatric nurses working under recently introduced job specific work systems than among public health nurses (PHNs) engaged in other public health services. (2) To identify work environment factors potentially contributing to burnout.Methods:Two groups were examined. The psychiatric group comprised 525 PHNs primarily engaged in public mental health services at public health centres (PHCs) that had adopted the job specific work system. The control group comprised 525 PHNs primarily engaged in other health services. Pines’ Burnout Scale was used to measure burnout. Respondents were classified by burnout score into three groups: A (mentally stable, no burnout); B (positive signs, risk of burnout); and C (burnout present, action required). Groups B and C were considered representative of “burnout”. A questionnaire was also prepared to investigate systems for supporting PHNs working at PHCs and to define emergency mental health service factors contributing to burnout.Results:Final respondents comprised 785 PHNs. Prevalence of burnout was significantly higher in the psychiatric group (59.2%) than in the control group (51.5%). Responses indicating lack of job control and increased annual frequency of emergency overtime services were significantly correlated with prevalence of burnout in the psychiatric group, but not in the control group.Conclusions:Prevalence of burnout is significantly higher for community psychiatric nurses than for PHNs engaged in other services. Overwork in emergency services and lack of job control appear to represent work environment factors contributing to burnout.
Acute childhood leukaemia and environmental exposure to potential sources of benzene and other hydrocarbons; a case-control study
Authors: Steffen C , Auclerc M F , Auvrignon A , Baruchel A , Kebaili K , Lambilliotte A , Leverger G , Sommelet D , Vilmer E , Hémon D , Clavel J 
Published: August 2004

Aim:To analyse the association between potential environmental exposure to hydrocarbons and the risk of acute childhood leukaemia.Methods:A hospital based multicentre case control study, stratified on centre, age, and sex, with 280 leukaemia cases and 285 controls was carried out. Data were collected by a standardised interview of the mothers.Results:No clear association was seen between maternal occupational exposure to hydrocarbons during pregnancy and leukaemia, or between residential traffic density and leukaemia. There was an association between dwellings neighbouring a petrol station or a repair garage during childhood and the risk of childhood leukaemia (OR 4.0, 95% CI 1.5 to 10.3), with a duration trend. The association, which appeared particularly strong for acute non-lymphocytic leukaemia (OR 7.7, 95% CI 1.7 to 34.3), was not altered by adjustment for potential confounding factors.Conclusions:Results showed an association between acute childhood leukaemia and dwellings neighbouring auto repair garages and petrol stations, which are benzene emitting sources. These findings could be due to chance, although the strength of the association and the duration trend are arguments for a causal association.
Airway inflammation in aluminium potroom asthma
Authors: Sjåheim T , Halstensen T S , Lund M B , Bjørtuft Ø , Drabløs P A , Malterud D , Kongerud J 
Published: August 2004

Aims:To examine whether asthma induced by exposure to aluminium potroom emissions (potroom asthma) is associated with inflammatory changes in the airways.Methods:Bronchial biopsy specimens from 20 asthmatic workers (8 non-smokers and 12 smokers), 15 healthy workers (8 non-smokers and 7 smokers), and 10 non-exposed controls (all non-smokers) were analysed. Immunohistofluorescent staining was performed to identify mucosal total leucocytes (CD45+leucocytes), neutrophils, and mast cells.Results:Median RBM thickness was significantly increased in both asthmatic workers (8.2 μm) and healthy workers (7.4 μm) compared to non-exposed controls (6.7 μm). Non-smoking asthmatic workers had significantly increased median density of lamina propria CD45+leucocytes (1519 cells/mm2v660 and 887 cells/mm2) and eosinophils (27 cells/mm2v10 and 3 cells/mm2) and significantly increased concentrations of exhaled NO (18.1 ppbv6.5 and 5.1 ppb) compared to non-smoking healthy workers and non-exposed controls. Leucocyte counts and exhaled NO concentrations varied with smoking habits and fewer leucocytes were observed in asthmatic smokers than in non-smokers Asthmatic smokers had significantly increased numbers of eosinophils in lamina propria compared to non-exposed controls (10v3 cells/mm2). Both eosinophilic and non-eosinophilic phenotypes of asthma were recognised in the potroom workers and signs of airway inflammation were also observed in healthy workers.Conclusions:Airway inflammation is a central feature of potroom asthma and exposure to potroom emissions induces pathological alterations similar to those described in other types of asthma. Cigarette smoking seems to affect the underlying mechanisms involved in asthma, as the cellular composition of airway mucosa appears different in asthmatic smokers and non-smokers.
Output power levels from mobile phones in different geographical areas; implications for exposure assessment
Authors: Lönn S , Forssén U , Vecchia P , Ahlbom A , Feychting M 
Published: August 2004

Background:The power level used by the mobile phone is one of the most important factors determining the intensity of the radiofrequency exposure during a call. Mobile phone calls made in areas where base stations are densely situated (normally urban areas) should theoretically on average use lower output power levels than mobile phone calls made in areas with larger distances between base stations (rural areas).Aims:To analyse the distribution of power levels from mobile phones in four geographical areas with different population densities.Methods:The output power for all mobile phone calls managed by the GSM operator Telia Mobile was recorded during one week in four defined areas (rural, small urban, suburban, and city area) in Sweden. The recording included output power for the 900 MHz and the 1800 MHz frequency band.Results:In the rural area, the highest power level was used about 50% of the time, while the lowest power was used only 3% of the time. The corresponding numbers for the city area were approximately 25% and 22%. The output power distribution in all defined urban areas was similar.Conclusion:In rural areas where base stations are sparse, the output power level used by mobile phones are on average considerably higher than in more densely populated areas. A quantitative assessment of individual exposure to radiofrequency fields is important for epidemiological studies of possible health effects for many reasons. Degree of urbanisation may be an important parameter to consider in the assessment of radiofrequency exposure from mobile phone use.
Antithrombotic activity of dermatan sulfate in heparin cofactor II-deficient mice
Authors: Vicente Cristina P. , He Li , Pavão Mauro S. G. , Tollefsen Douglas M. 
Published: August 2004

AbstractHeparin cofactor II (HCII) is a plasma protein that inhibits thrombin rapidly in the presence of dermatan sulfate or heparin. We previously reported that the time to thrombotic occlusion of the carotid artery after photochemical injury was shorter in HCII-deficient mice than in wild-type control animals. In this paper, we describe the antithrombotic activity of dermatan sulfate in wild-type and HCII-deficient mice. Intravenous administration of porcine skin dermatan sulfate induced a dose-dependent prolongation of the carotid artery occlusion time in HCII+/+ mice that was not observed in HCII-/- animals. Pharmacokinetic studies suggested that porcine skin dermatan sulfate expresses antithrombotic activity after being transferred from the plasma to sites in the vessel wall. Using invertebrate dermatan sulfate preparations, we showed that N-acetylgalactosamine-4-O-sulfate residues are required for the HCII-dependent antithrombotic effect. Furthermore, the invertebrate dermatan sulfates, which have higher charge densities than mammalian dermatan sulfate, slightly prolonged the thrombotic occlusion time of HCII-/- mice. These results indicate that HCII mediates the antithrombotic effect of porcine skin dermatan sulfate after injury to the carotid arterial endothelium in mice, whereas more highly charged dermatan sulfates possess weak antithrombotic activity independent of HCII. (Blood. 2004;104:3965-3970)