bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Synonymous Mutation in
Yersinia enterocolitica yopE
Affects the Function of the YopE Type III Secretion Signal
Authors: Ramamurthi Kumaran S. , Schneewind Olaf 
Published: January 2005

ABSTRACT

Yersinia
spp. inject virulence proteins called Yops into the cytosol of target eukaryotic cells in an effort to evade phagocytic killing via a dedicated protein-sorting pathway termed type III secretion. Previous studies have proposed that, unlike other protein translocation mechanisms, Yops are not recognized as substrates for secretion via a solely proteinaceous signal. Rather, at least some of this information may be encoded within
yop
mRNA. Herein, we report that the first seven codons of
yopE
, when fused to the reporter protein neomycin phosphotransferase (Npt), are sufficient for the secretion of YopE
1-7
-Npt when type III secretion is induced in vitro. Systematic mutagenesis of
yopE
codons 1 to 7 reveals that, like
yopQ
, codons 2, 3, 5, and 7 are sensitive to mutagenesis, thereby defining the first empirical similarity between the secretion signals of two type III secreted substrates. Like that of
yopQ
, the secretion signal of
yopE
exhibits a bipartite nature. This is manifested by the ability of codons 8 to 15 to suppress point mutations in the minimal secretion signal that change the amino acid specificities of particular codons or that induce alterations in the reading frame. Further, we have identified a single nucleotide position in codon 3 that, when mutated, conserves the predicted amino acid sequence of the YopE
1-7
-Npt but abrogates secretion of the reporter protein. When introduced into the context of the full-length
yopE
gene, the single-nucleotide mutation reduces the type III injection of YopE into HeLa cells, even though the predicted amino acid sequence remains the same. Thus,
yopE
mRNA appears to encode a property that mediates the type III injection of YopE.
ThebldCDevelopmental Locus ofStreptomyces coelicolorEncodes a Member of a Family of Small DNA-Binding Proteins Related to the DNA-Binding Domains of the MerR Family
Authors: Hunt Alison C. , Servín-González Luis , Kelemen Gabriella H. , Buttner Mark J. 
Published: January 2005

ABSTRACTThebldClocus, required for formation of aerial hyphae inStreptomyces coelicolor, was localized by map-based cloning to the overlap between cosmids D17 and D25 of a minimal ordered library. Subcloning and sequencing showed thatbldCencodes a member of a previously unrecognized family of small (58- to 78-residue) DNA-binding proteins, related to the DNA-binding domains of the MerR family of transcriptional activators. BldC family members are found in a wide range of gram-positive and gram-negative bacteria. ConstructedΔbldCmutants were defective in differentiation and antibiotic production. They failed to form an aerial mycelium on minimal medium and showed severe delays in aerial mycelium formation on rich medium. In addition, they failed to produce the polyketide antibiotic actinorhodin, andbldCwas shown to be required for normal and sustained transcription of the pathway-specific activator geneactII-orf4. AlthoughΔbldCmutants produced the tripyrrole antibiotic undecylprodigiosin, transcripts of the pathway-specific activator gene (redD) were reduced to almost undetectable levels after 48 h in thebldCmutant, in contrast to thebldC+parent strain in whichredDtranscription continued during aerial mycelium formation and sporulation. This suggests thatbldCmay be required for maintenance ofredDtranscription during differentiation.bldCis expressed from a single promoter. S1 nuclease protection assays and immunoblotting showed thatbldCis constitutively expressed and that transcription ofbldCdoes not depend on any of the other knownbldgenes. ThebldC18mutation that originally defined the locus causes a Y49C substitution that results in instability of the protein.
The Periplasmic α-Carbonic Anhydrase Activity of
Helicobacter pylori
Is Essential for Acid Acclimation
Authors: Marcus Elizabeth A. , Moshfegh Amiel P. , Sachs George , Scott David R. 
Published: January 2005

ABSTRACT

The role of the periplasmic α-carbonic anhydrase (α-CA) (HP1186) in acid acclimation of
Helicobacter pylori
was investigated. Urease and urea influx through UreI have been shown to be essential for gastric colonization and for acid survival in vitro. Intrabacterial urease generation of NH
3
has a major role in regulation of periplasmic pH and inner membrane potential under acidic conditions, allowing adequate bioenergetics for survival and growth. Since α-CA catalyzes the conversion of CO
2
to HCO
3
−
, the role of CO
2
in periplasmic buffering was studied using an α-CA deletion mutant and the CA inhibitor acetazolamide. Western analysis confirmed that α-CA was bound to the inner membrane. Immunoblots and PCR confirmed the absence of the enzyme and the gene in the α-CA knockout. In the mutant or in the presence of acetazolamide, there was an ∼3 log
10
decrease in acid survival. In acid, absence of α-CA activity decreased membrane integrity, as observed using membrane-permeant and -impermeant fluorescent DNA dyes. The increase in membrane potential and cytoplasmic buffering following urea addition to wild-type organisms in acid was absent in the α-CA knockout mutant and in the presence of acetazolamide, although UreI and urease remained fully functional. At low pH, the elevation of cytoplasmic and periplasmic pH with urea was abolished in the absence of α-CA activity. Hence, buffering of the periplasm to a pH consistent with viability depends not only on NH
3
efflux from the cytoplasm but also on the conversion of CO
2
, produced by urease, to HCO
3
−
by the periplasmic α-CA.
Mutational Analysis of
nocK
and
nocL
in the Nocardicin A Producer
Nocardia uniformis
Authors: Kelly Wendy L. , Townsend Craig A. 
Published: January 2005

ABSTRACT

The nocardicins are a family of monocyclic β-lactam antibiotics produced by the actinomycete
Nocardia uniformis
subsp.
tsuyamanensis
ATCC 21806. The most potent of this series is nocardicin A, containing a
syn
-configured oxime moiety, an uncommon feature in natural products. The nocardicin A biosynthetic gene cluster was recently identified and found to encode proteins in keeping with nocardicin A production, including the nocardicin
N
-oxygenase, NocL, in addition to genes of undetermined function, such as
nocK
, which bears similarities to a broad family of esterases. The latter was hypothesized to be involved in the formation of the critical β-lactam ring. While previously shown to effect oxidation of the 2′-amine of nocardicin C to provide nocardicin A, it was uncertain whether NocL was the only N-oxidizing enzyme required for nocardicin A biosynthesis. To further detail the role of NocL in nocardicin production in
N. uniformis
, and to examine the function of
nocK
, a method for the transformation of
N. uniformis
protoplasts to inactivate both
nocK
and
nocL
was developed and applied. A reliable protocol is reported to achieve both insertional disruption and in
trans
complementation in this strain. While the
nocK
mutant still produced nocardicin A at levels near that seen for wild-type
N. uniformis
, and therefore has no obvious role in nocardicin biosynthesis, the
nocL
disruptant failed to generate the oxime-containing metabolite. Nocardicin A production was restored in the
nocL
mutant upon in
trans
expression of the gene. Furthermore, the
nocL
mutant accumulated the biosynthetic intermediate nocardicin C, confirming its role as the sole oxime-forming enzyme required for production of nocardicin A.
Identification and Complementation of a Mutation Associated with Loss of
Mycoplasma pneumoniae
Virulence-Specific Proteins B and C
Authors: Waldo Robert H. , Jordan Jarrat L. , Krause Duncan C. 
Published: January 2005

ABSTRACT

A mutation in gene MPN142 (
orf6
) was identified in the
Mycoplasma pneumoniae
cytadherence mutant III-4. MPN142 encodes virulence-specific proteins P90 and P40 (proteins B and C, respectively). Analysis of MPN142 in a cytadhering revertant and complementation using a recombinant wild-type allele confirmed the role of this mutation in the cytadherence defect.
Vibrios Commonly Possess Two Chromosomes
Authors: Okada Kazuhisa , Iida Tetsuya , Kita-Tsukamoto Kumiko , Honda Takeshi 
Published: January 2005

ABSTRACT
The prevalence of the two-chromosome configuration was investigated in 34 species of vibrios and closely related species. Pulsed-field gel electrophoresis of undigested genomic DNA suggested that vibrios commonly have two chromosomes. The size of the large chromosome is predominantly within a narrow range (3.0 to 3.3 Mb), whereas the size of the small chromosome varies considerably among the vibrios (0.8 to 2.4 Mb). This fact suggests that the structure of the small chromosome is more flexible than that of the large chromosome during the evolution of vibrios.
Characterization of the Phd Repressor-Antitoxin Boundary
Authors: McKinley James Estle , Magnuson Roy David 
Published: January 2005

ABSTRACT
The P1 plasmid addiction operon (a classic toxin-antitoxin system) encodes Phd, an unstable 73-amino-acid repressor-antitoxin protein, and Doc, a stable toxin. It was previously shown by deletion analysis that the N terminus of Phd was required for repressor activity and that the C terminus was required for antitoxin activity. Since only a quarter of the protein or less was required for both activities, it was hypothesized that Phd might have a modular organization. To further test the modular hypothesis, we constructed and characterized a set of 30 point mutations in the third and fourth quarters of Phd. Four mutations (PhdA36H, V37A, I38A, and F44A) had major defects in repressor activity. Five mutations (PhdD53A, D53R, E55A, F56A, and F60A) had major defects in antitoxin activity. As predicted by the modular hypothesis, point mutations affecting each activity belonged to disjoint, rather than overlapping, sets and were separated rather than interspersed within the linear sequence. A final deletion experiment demonstrated that the C-terminal 24 amino acid residues of Phd (preceded by a methionine) retained full antitoxin activity.
Evidence for Two Flagellar Stators and Their Role in the Motility of
Pseudomonas aeruginosa
Authors: Toutain Christine M. , Zegans Michael E. , O'Toole George A. 
Published: January 2005

ABSTRACT

Pseudomonas aeruginosa
is a ubiquitous bacterium capable of twitching, swimming, and swarming motility. In this study, we present evidence that
P. aeruginosa
has two flagellar stators, conserved in all pseudomonads as well as some other gram-negative bacteria. Either stator is sufficient for swimming, but both are necessary for swarming motility under most of the conditions tested, suggesting that these two stators may have different roles in these two types of motility.
Deletion Analysis of the Carboxyl-Terminal Region of the PomB Component of the
Vibrio alginolyticus
Polar Flagellar Motor
Authors: Yakushi Toshiharu , Hattori Naoko , Homma Michio 
Published: January 2005

ABSTRACT

The stator of the sodium-driven flagellar motor of
Vibrio alginolyticus
is a membrane protein complex composed of four PomA and two PomB subunits. PomB has a peptidoglycan-binding motif in the C-terminal region. In this study, four kinds of PomB deletions in the C terminus were constructed. None of the deletion proteins restored motility of the Δ
pomB
strain. The PomA protein was coisolated with all of the PomB derivatives under detergent-solubilized conditions. Homotypic disulfide cross-linking of all of the deletion derivatives through naturally occurring Cys residues was detected. We conclude that the C-terminal region of PomB is essential for motor function but not for oligomerization of PomB with itself or PomA.
The BpsIR Quorum-Sensing System of
Burkholderia pseudomallei
Authors: Song Yan , Xie Chao , Ong Yong-Mei , Gan Yunn-Hwen , Chua Kim-Lee 
Published: January 2005

ABSTRACT

BpsIR, a LuxIR quorum-sensing homolog, is required for optimal expression of virulence and secretion of exoproducts in
Burkholderia pseudomallei
. Cell density-dependent expression of
bpsI
and
bpsR
, the positive regulation of
bpsIR
expression by BpsR, and the synthesis of
N
-octanoyl-homoserine lactone (C8HSL) by BpsI are described in this report.
The Purine Efflux Pump PbuE in
Bacillus subtilis
Modulates Expression of the PurR and G-Box (XptR) Regulons by Adjusting the Purine Base Pool Size
Authors: Nygaard Per , Saxild Hans H. 
Published: January 2005

ABSTRACT

In
Bacillus subtilis
, the expression of genes encoding enzymes and other proteins involved in purine de novo synthesis and salvage is affected by purine bases and phosphoribosylpyrophosphate (PRPP). The transcription of the genes belonging to the PurR regulon is negatively regulated by the PurR protein and PRPP. The expression of the genes belonging to the G-box (XptR) regulon, including the
pbuE
gene, is negatively regulated by a riboswitch-controlled transcription termination mechanism. The G-box regulon effector molecules are hypoxanthine and guanine.
pbuE
encodes a purine base efflux pump and is now recognized as belonging to a third purine regulon. The expression of the
pbuE
gene is positively regulated by a riboswitch that recognizes adenine. Here we show that the expression of
pbuE
′
-lacZ
transcriptional fusions are induced by adenine to the highest extent in mutants which do not express a functional PbuE pump. In a mutant defective in the metabolism of adenine, the
ade apt
mutant, we found a high intracellular level of adenine and constitutive high levels of PbuE. A growth test using a purine auxotroph provided further evidence for the role of PbuE in lowering the intracellular concentration of purine bases, including adenine. Purine analogs also affect the expression of
pbuE
, which might be of importance for the protection against toxic analogs. In a mutant that overexpresses PbuE, the expression of genes belonging to the PurR regulon was increased. Our findings provide further evidence for important functions of the PbuE protein, such as acting as a pump that lowers the purine base pool and affects the expression of the G-box and PurR regulons, including
pbuE
itself, and as a pump involved in protection against toxic purine base analogs.
Cloning, Purification, and Enzymatic Properties of Dipeptidyl Peptidase IV from the Swine Pathogen
Streptococcus suis
Authors: Jobin Marie-Claude , Martinez Gabriela , Motard Julie , Gottschalk Marcelo , Grenier Daniel 
Published: January 2005

ABSTRACT

In this study, the dipeptidyl peptidase IV (DPP IV) of the swine pathogen
Streptococcus suis
was cloned, overexpressed in
Escherichia coli
, and characterized. The coding region comprises 2,268 nucleotides containing an open reading frame that codes for a 755-amino-acid protein with a calculated molecular mass of 85 kDa. The amino acid sequence contained the sequence Gly-X-Ser-X-X-Gly, which is a consensus motif flanking the active-site serine shared by serine proteases. The recombinant DPP IV showed a high affinity for the synthetic peptide glycine-proline-
p
-nitroanilide and was strongly inhibited by Hg
2+
and diprotin A.
Conjugational Genetic Exchange in the Hyperthermophilic Archaeon
Sulfolobus acidocaldarius
: Intragenic Recombination with Minimal Dependence on Marker Separation
Authors: Hansen Josh E. , Dill Amy C. , Grogan Dennis W. 
Published: January 2005

ABSTRACT

In
Sulfolobus acidocaldarius
conjugation assays, recombinant frequency was relatively constant for marker separations from 1,154 bp down to about 50 bp and readily detectable at 10 bp. Three-factor crosses revealed little, if any, genetic linkage over distances of 500 to 600 bp, and large deletion mutants were good donors but poor recipients in matings. The results indicate that most intragenic recombination events occur at one of the mutations, not in the interval between them.
Stepped care in psychological therapies: access, effectiveness and efficiency
Authors: Bower Peter , Gilbody Simon 
Published: January 2005

BackgroundThere is a significant gap between the demand for psychological therapy services and the available supply. One proposal to overcome this problem is to increase efficiency of provision through the adoption of briefer ‘minimal interventions' within stepped care models.AimsTo examine the theoretical underpinnings of stepped care, together with the practicalities of the adoption of this system of care.MethodNarrative literature review.ResultsThe potential clinical and economic benefits of stepped care are dependent upon underlying assumptions of equivalence in terms of clinical outcomes, efficiency in terms of resource use and costs, and acceptability of ‘minimal interventions' to patients and therapists. Illustrative studies of these issues are considered.ConclusionsAlthough psychological services might benefit from the adoption of the stepped care model, a substantial research agenda needs to be fulfilled before a judgement can be made as to whether stepped care might be an efficient method of delivering psychological services.
Predicting schizophrenia: findings from the Edinburgh High-Risk Study
Authors: Johnstone Eve C. , Ebmeier Klaus P. , Miller Patrick , Owens David G. C. , Lawrie Stephen M. 
Published: January 2005

BackgroundThe hypothesis that schizophrenia is neurodevelopmental was investigated in a prospective study of young people with a postulated 10–15% risk for the development of schizophrenia.AimsTo determine premorbid variables distinguishing high-risk people who will go on to develop schizophrenia from those who will not.MethodA high-risk sample of 163 young adults with two relatives with schizophrenia was recruited. They and 36 controls were serially examined. Baseline measures were compared between those who did develop schizophrenia, a well control group, a well high-risk group and high-risk participants with partial or isolated psychotic symptoms.ResultsOf those at high risk, 20 developed schizophrenia within 2½ years. More experienced isolated or partial psychotic symptoms. Those who developed schizophrenia differed from those who did not on social anxiety, withdrawal and other schizotypal features. The whole high-risk sample differed from the control group on developmental and neuropsychological variables.ConclusionsThe genetic component of schizophrenia affects many more individuals than will develop the illness, and partial impairment can be found in them. Highly significant predictors of the development of schizophrenia are detectable years before onset.
Duration of illness and treatment effects on hippocampal volume in male patients with schizophrenia
Authors: Chakos Miranda H. , Schobel Scott A. , Gu Hongbin , Gerig Guido , Bradford Daniel , Charles Cecil , Lieberman Jeffrey A. 
Published: January 2005

BackgroundReduced hippocampal volume is a consistently described structural abnormality in schizophrenia but its cause and timing are not known.AimsTo examine the relationship of duration of schizophrenic illness and treatment effects with hippocampal volumes.MethodQuantitative 1.5 T magnetic resonance imaging brain scans of young male patients in the early stage of schizophrenic illness were compared with those of chronically ill older patients. Scans were also acquired for controls matched to both patient groups for age and handedness. Duration of illness was recorded and severity of symptoms assessed with the Positive and Negative Syndrome Scale.ResultsThe patients with schizophrenia had smaller hippocampal volumes than the controls. The volume reduction was larger in older patients than in young, compared with age-matched controls. In the early illness group atypical antipsychotics rather than haloperidol were associated with larger hippocampal volumes even after controlling for differences in illness severity Conclusions The greater reduction of hippocampal volume in people with chronic v. early illness, after controlling for illness severity and age, supports the hypothesis of progressive hippocampal reduction in males with schizophrenia. Atypical antipsychotics early in illness may protect against this.
Neurocognitive impairment in euthymic patients with bipolar affective disorder
Authors: Thompson Jill M. , Gallagher Peter , Hughes John H. , Watson Stuart , Gray John M. , Ferrier I. Nicol , Young Allan H. 
Published: January 2005

BackgroundPersistent impairments in neurocognitive function have been described in patients with bipolar disorder whose disease is in remission. However, methodological issues such as the effect of residual mood symptoms and hypercortisolaemia may confound such studies.AimsTo assess neurocognitive functioning in prospectively verified euthymic patients with bipolar disorder.MethodSixty-three patients with bipolar disorder and a matched control group completed a comprehensive neurocognitive test battery. Euthymia was confirmed in the patient group by prospective clinical ratings over 1 month prior to testing. Saliva samples were collected to profile basal cortisol secretion.ResultsPatients were significantly impaired across a broad range of cognitive domains. Across the domains tested, clinically significant impairment was observed in 3% to 42% of patients. Deficits were not causally associated with residual mood symptoms or hypercortisolaemia.ConclusionsNeurocognitive impairment persists in patients whose bipolar disorder is in remission. This may represent a trait abnormality and be a marker of underlying neurobiological dysfunction.
Major depression and its correlates in primary care settings in six countries
Authors: De Almeida Fleck Marcelo Pio , Simon Gregory , Herrman Helen , Bushnell Donald , Martin Mona , Patrick Donald 
Published: January 2005

BackgroundFew published studies address depression outcomes in primary care from a cross-cultural perspective.AimsTo define baseline factors associated with 9-month clinical outcome: across six countries.MethodAdults meeting criteria for current major depression were recruited from primary care clinics in Australia, Brazil, Israel, Spain, Russia and the USA; 968 patients were assessed at the 9-month follow-up. Predictors of complete remission were examined using logistic regression with a hierarchical model.ResultsRates of complete remission in the six sites ranged from 25% to 48%. Logistic regression using pooled data showed that education, key life events and the Quality of Life Depression Scale score at baseline were the final predictors of complete remission, adjusting for centres, socio-demographic data, severity of depression, comorbidity and general quality of life. Variation in predictors across sites was not statistically significant.ConclusionsThe two major findings of this study were the low proportion of people achieving complete remission at follow-up across the six sites, and that some baseline characteristics (education, Quality of Life Depression Scale score and key life events) are modest predictors of outcome in depression.