bluuebunny/crossref_metadata_2025_split huggingface dataset:
Feedback-Resistant Mutations in
Bacillus subtilis
Glutamine Synthetase Are Clustered in the Active Site
Authors: Fisher Susan H. , Wray Lewis V. 
Published: August 2006

ABSTRACT

The feedback-inhibited form of
Bacillus subtilis
glutamine synthetase regulates the activity of the TnrA transcription factor through a protein-protein interaction that prevents TnrA from binding to DNA. Five mutants containing feedback-resistant glutamine synthetases (E65G, S66P, M68I, H195Y, and P318S) were isolated by screening for colonies capable of cross-feeding Gln
−
cells. In vitro enzymatic assays revealed that the mutant enzymes had increased resistance to inhibition by glutamine, AMP, and methionine sulfoximine. The mutant proteins had a variety of enzymatic alterations that included changes in the levels of enzymatic activity and in substrate

K
m

values. Constitutive expression of TnrA- and GlnR-regulated genes was seen in all five mutants. In gel mobility shift assays, the E65G and S66P enzymes were unable to inhibit TnrA DNA binding, while the other three mutant proteins (M68I, H195Y, and P318S) showed partial inhibition of TnrA DNA binding. A homology model of
B. subtilis
glutamine synthetase revealed that the five mutated amino acid residues are located in the enzyme active site. These observations are consistent with the hypothesis that glutamine and AMP bind at the active site to bring about feedback inhibition of glutamine synthetase.
Requirement for
Vibrio cholerae
Integration Host Factor in Conjugative DNA Transfer
Authors: McLeod Sarah M. , Burrus Vincent , Waldor Matthew K. 
Published: August 2006

ABSTRACT

The requirement for host factors in the transmission of integrative and conjugative elements (ICEs) has not been extensively explored. Here we tested whether integration host factor (IHF) or Fis, two host-encoded nucleoid proteins, are required for transfer of SXT, a
Vibrio cholerae
-derived ICE that can be transmitted to many gram-negative species. Fis did not influence the transfer of SXT to or from
V. cholerae
. In contrast, IHF proved to be required for
V. cholerae
to act as an SXT donor. In the absence of IHF,
V. cholerae
displayed a modest defect for serving as an SXT recipient. Surprisingly, SXT integration into or excision from the
V. cholerae
chromosome, which requires an SXT-encoded integrase related to λ integrase, did not require IHF. Therefore, the defect in SXT transmission in the
V. cholerae
IHF mutant is probably not related to IHF's ability to promote DNA recombination. The
V. cholerae
IHF mutant was also highly impaired as a donor of RP4, a broad-host-range conjugative plasmid. Thus, the
V. cholerae
IHF mutant appears to have a general defect in conjugation.
Escherichia coli
IHF mutants were not impaired as donors or recipients of SXT or RP4, indicating that IHF is a
V. cholerae
-specific conjugation factor.
Mutator and Antimutator Effects of the Bacteriophage P1hotGene Product
Authors: Chikova Anna K. , Schaaper Roel M. 
Published: August 2006

ABSTRACTThe Hot (homolog of theta) protein of bacteriophage P1 can substitute for theEscherichia coliDNA polymerase III θ subunit, as evidenced by its stabilizing effect on certaindnaQmutants that carry an unstable polymerase III ε proofreading subunit (antimutator effect). Here, we show that Hot can also cause an increase in the mutability of variousE. colistrains (mutator effect). Thehotmutator effect differs from the one caused by the lack of θ. Experiments using chimeric θ/Hot proteins containing various domains of Hot and θ along with a series of point mutants show that both N- and C-terminal parts of each protein are important for stabilizing the ε subunit. In contrast, the N-terminal part of Hot appears uniquely responsible for its mutator activity.
Transport of Multidrug Resistance Substrates by theStreptococcus agalactiaeHemolysin Transporter
Authors: Gottschalk Birgit , Bröker Gerd , Kuhn Melanie , Aymanns Simone , Gleich-Theurer Ute , Spellerberg Barbara 
Published: August 2006

ABSTRACTStreptococcus agalactiae(group B streptococcus [GBS]) causes neonatal sepsis, pneumonia, and meningitis, as well as infections of the bovine udder. TheS. agalactiaehemolysin is regarded as an important virulence factor, and hemolysin expression is dependent on thecylgene cluster.cylAandcylBencode the ATP binding and transmembrane domains of a typical ATP binding cassette (ABC) transporter. The deduced proteins contain the signature sequence of a multidrug resistance (MDR) transporter, and mutation of the genes results in a nonhemolytic and nonpigmented phenotype. To further elucidate the function of the putative transporter, nonpolar deletion mutants ofcylAwere constructed. These mutants are nonhemolytic and can be complemented by the transporter genes. Wild-type strain and nonhemolyticcylAandcylKdeletion mutants were exposed to known substrates of MDR transporters. Mutation ofcylAsignificantly impaired growth in the presence of daunorubicin, doxorubicin, and rhodamine 6G and resulted in a decreased export of doxorubicin from the cells. The mutation ofcylK, a gene of unknown function located downstream fromcylA, caused a loss of hemolysis but had no effect on the transport of MDR substrates. Furthermore, the hemolytic activity of the wild-type strain was inhibited by reserpine in a dose-dependent manner. We conclude that CylAB closely resembles an ABC-type MDR transporter and propose that the GBS hemolysin molecule represents a natural substrate of the transporter.
Comparison of the Genome Sequence of the Poultry PathogenBordetella aviumwith Those ofB. bronchiseptica,B. pertussis, andB. parapertussisReveals Extensive Diversity in Surface Structures Associated with Host Interaction
Authors: Sebaihia Mohammed , Preston Andrew , Maskell Duncan J. , Kuzmiak Holly , Connell Terry D. , King Natalie D. , Orndorff Paul E. , Miyamoto David M. , Thomson Nicholas R. , Harris David , Goble Arlette , Lord Angela , Murphy Lee , Quail Michael A. , Rutter Simon , Squares Robert , Squares Steven , Woodward John , Parkhill Julian , Temple Louise M. 
Published: August 2006

ABSTRACTBordetella aviumis a pathogen of poultry and is phylogenetically distinct fromBordetella bronchiseptica,Bordetella pertussis, andBordetella parapertussis, which are other species in theBordetellagenus that infect mammals. In order to understand the evolutionary relatedness ofBordetellaspecies and further the understanding of pathogenesis, we obtained the complete genome sequence ofB. aviumstrain 197N, a pathogenic strain that has been extensively studied. With 3,732,255 base pairs of DNA and 3,417 predicted coding sequences, it has the smallest genome and gene complement of the sequenced bordetellae. In this study, the presence or absence of previously reported virulence factors fromB. aviumwas confirmed, and the genetic bases for growth characteristics were elucidated. Over 1,100 genes present inB. aviumbut not inB. bronchisepticawere identified, and most were predicted to encode surface or secreted proteins that are likely to define an organism adapted to the avian rather than the mammalian respiratory tracts. These include genes coding for the synthesis of a polysaccharide capsule, hemagglutinins, a type I secretion system adjacent to two very large genes for secreted proteins, and unique genes for both lipopolysaccharide and fimbrial biogenesis. Three apparently complete prophages are also present. The BvgAS virulence regulatory system appears to have polymorphisms at a poly(C) tract that is involved in phase variation in other bordetellae. A number of putative iron-regulated outer membrane proteins were predicted from the sequence, and this regulation was confirmed experimentally for five of these.
Class 1 Integrons Potentially Predating the Association with Tn402-Like Transposition Genes Are Present in a Sediment Microbial Community
Authors: Stokes H. W. , Nesbø Camilla L. , Holley Marita , Bahl Martin I. , Gillings Michael R. , Boucher Yan 
Published: August 2006

ABSTRACTIntegrons are genetic elements that contribute to lateral gene transfer in bacteria as a consequence of possessing a site-specific recombination system. This system facilitates the spread of genes when they are part of mobile cassettes. Most integrons are contained within chromosomes and are confined to specific bacterial lineages. However, this is not the case for class 1 integrons, which were the first to be identified and are one of the single biggest contributors to multidrug-resistant nosocomial infections, carrying resistance to many antibiotics in diverse pathogens on a global scale. The rapid spread of class 1 integrons in the last 60 years is partly a result of their association with a specific suite of transposition functions, which has facilitated their recruitment by plasmids and other transposons. The widespread use of antibiotics has acted as a positive selection pressure for bacteria, especially pathogens, which harbor class 1 integrons and their associated antibiotic resistance genes. Here, we have isolated bacteria from soil and sediment in the absence of antibiotic selection. Class 1 integrons were recovered from four different bacterial species not known to be human pathogens or commensals. All four integrons lacked the transposition genes previously considered to be a characteristic of this class. At least two of these integrons were located on a chromosome, and none of them possessed antibiotic resistance genes. We conclude that novel class 1 integrons are present in a sediment environment in various bacteria of the β-proteobacterial class. These data suggest that the dispersal of this class may have begun before the “antibiotic era.”
Salicylic Acid Activates Sigma Factor B by
rsbU
-Dependent and -Independent Mechanisms
Authors: Palma Marco , Bayer Arnold , Kupferwasser Leon I. , Joska Tammy , Yeaman Michael R. , Cheung Ambrose 
Published: August 2006

ABSTRACT

Salicylic acid (SAL) may impact
Staphylococcus aureus
virulence by activating the
sigB
operon (
rsbU-V-W-sigB
), thus leading to reductions in alpha-toxin production and decreased fibronectin binding (L. I. Kupferwasser et al., J. Clin. Investig. 112:222-233, 2003). As these prior studies were performed in strain RN6390 (an
rsbU
mutant) and its
rsbU
-repaired variant, SH1000, the current investigation was designed to determine if the SAL effect occurs via
rsbU-
and/or
rsbV-
dependent pathways in an
rsbU-
intact
S. aureus
strain (FDA486). We thus quantified the transcription from two
sigB
-dependent promoters (
asp
23 and
sarA
P3) in FDA486 in response to SAL exposure in vitro, using isogenic single-knockout constructs of
rsbU
,
rsbV
, or
rsbW
and a green fluorescent protein reporter system. SAL induced
sarA
P3 and
asp23
promoter activities in a dose-dependent manner in the parental strain. In contrast,
sigB
activation by SAL was progressively more mitigated in the
rsbU
and
rsbV
mutants. As predicted, SAL caused significant reductions in both alpha-toxin production and fibrinogen and fibronectin binding in the parental strain. The extent of these reductions, compared with the parent, was reduced in the
rsb
mutants (
rsbV
>
rsbU
), especially at low SAL concentrations. Since generation of the free SigB protein usually requires a sequential
rsbU-V-W-sigB
activation cascade, the present phenotypic and genotypic data suggest key roles for both
rsbU
and
rsbV
in SAL-mediated activation of
sigB
in strains with a fully intact
sigB
operon.
International survey of seat belt use exemptions
Authors: Weiss H , Sirin H , Levine J A , Sauber E 
Published: August 2006

Background:Substantial evidence of seatbelt efficacy has been shown by several studies, and it is widely recommended that motor vehicle occupants use properly fitted seat belts. However, some (but a heretofore unknown number of) countries with national seat belt laws permit various exemptions which may lower use rates. The aim of this study was to survey the variety of exemptions to national seat belt laws.Methods:This investigation relied on identifying respondents from national traffic safety agencies, other governmental and non-governmental organizations, Internet searches, personal contacts, and other sources. Questionnaires were deployed through a web based survey supplemented by email and postal versions.Results:Responses were received from 30 countries of which 28 (93.7%) had a national seat belt law. About two thirds (63.7%) of the 28 national laws applied to both front and back seat passengers. The leading exemption types included vehicles made before a certain year (n = 13), antique vehicles (n = 12), military vehicles (n = 11), buses (n = 9), and emergency vehicles (n = 8). Most responding countries reported one or more specific categories of individuals as exempt including those with medical exemptions (n = 20), taxi drivers (n = 11), police (n = 9), emergency medical personnel (n = 8), physically disabled people (n = 6), and pregnant women (n = 6). Out of 26 responses to the question regarding current level of enforcement, 42.3% felt enforcement was “very good or good” and 57.7% characterized it as “fair or poor”.Conclusions:This study represents one of the largest international traffic law surveys reported. Most national seatbelt laws offer perilous exemptions to a broad array of vehicle types and road user groups. These findings, coupled with concern over the level of enforcement in the majority of countries surveyed, suggest that international road safety efforts have a long way to go to improve coverage and enforcement of national seat belt laws.
Economic disparity in bicycle helmet use by children six years after the introduction of legislation
Authors: Macpherson A K , Macarthur C , To T M , Chipman M L , Wright J G , Parkin P C 
Published: August 2006

Background:Studies evaluating the effectiveness of bicycle helmet legislation often focus on short term outcomes. The long term effect of helmet legislation on bicycle helmet use is unknown.Objective:To examine bicycle helmet use by children six years after the introduction of the law, and the influence of area level family income on helmet use.Methods:The East York (Toronto) health district (population 107 822) was divided into income areas (designated as low, mid, and high) based on census tract data from Statistics Canada. Child cyclists were observed at 111 preselected sites (schools, parks, residential streets, and major intersections) from April to October in the years 1995–1997, 1999, and 2001. The frequency of helmet use was determined by year, income area, location, and sex. Stratified analysis was used to quantify the relation between income area and helmet use, after controlling for sex and bicycling location.Results:Bicycle helmet use in the study population increased from a pre-legislation level of 45% in 1995 to 68% in 1997, then decreased to 46% by 2001. Helmet use increased in all three income areas from 1995 to 1997, and remained above pre-legislation rates in high income areas (85% in 2001). In 2001, six years post-legislation, the proportion of helmeted cyclists in mid and low income areas had returned to pre-legislation levels (50% and 33%, respectively). After adjusting for sex and location, children riding in high income areas were significantly more likely to ride helmeted than children in low income areas across all years (relative risk = 3.4 (95% confidence interval, 2.7 to 4.3)).Conclusion:Over the long term, the effectiveness of bicycle helmet legislation varies by income area. Alternative, concurrent, or ongoing strategies may be necessary to sustain bicycle helmet use among children in mid and low income areas following legislation.
The properties of the International Classification of the External Cause of Injury when used as an instrument for injury prevention research
Authors: Scott D , Harrison J , Purdie D , Bain C , Najman J , Nixon J , Spinks A B , McClure R J 
Published: August 2006

Objective:To demonstrate properties of the International Classification of the External Cause of Injury (ICECI) as a tool for use in injury prevention research.Methods:The Childhood Injury Prevention Study (CHIPS) is a prospective longitudinal follow up study of a cohort of 871 children 5–12 years of age, with a nested case crossover component. The ICECI is the latest tool in the International Classification of Diseases (ICD) family and has been designed to improve the precision of coding injury events. The details of all injury events recorded in the study, as well as all measured injury related exposures, were coded using the ICECI. This paper reports a substudy on the utility and practicability of using the ICECI in the CHIPS to record exposures. Interrater reliability was quantified for a sample of injured participants using the Kappa statistic to measure concordance between codes independently coded by two research staff.Results:There were 767 diaries collected at baseline and event details from 563 injuries and exposure details from injury crossover periods. There were no event, location, or activity details which could not be coded using the ICECI. Kappa statistics for concordance between raters within each of the dimensions ranged from 0.31 to 0.93 for the injury events and 0.94 and 0.97 for activity and location in the control periods.Discussion:This study represents the first detailed account of the properties of the ICECI revealed by its use in a primary analytic epidemiological study of injury prevention. The results of this study provide considerable support for the ICECI and its further use.
Parental smoking and children’s respiratory health: independent effects of prenatal and postnatal exposure
Authors: Pattenden Sam , Antova Temenuga , Neuberger Manfred , Nikiforov Bojidar , De Sario Manuela , Grize Leticia , Heinrich Joachim , Hruba Frantiska , Janssen Nicole , Luttmann-Gibson Heike , Privalova Larissa , Rudnai Peter , Splichalova Anna , Zlotkowska Renata , Fletcher Tony 
Published: August 2006

Objectives:Adverse effects have been reported of prenatal and/or postnatal passive exposure to smoking on children’s health. Uncertainties remain about the relative importance of smoking at different periods in the child’s life. We investigate this in a pooled analysis, on 53 879 children from 12 cross-sectional studies—components of the PATY study (Pollution And The Young).Methods:Effects were estimated, within each study, of three exposures: mother smoked during pregnancy, parental smoking in the first two years, current parental smoking. Outcomes were: wheeze, asthma, “woken by wheeze”, bronchitis, nocturnal cough, morning cough, “sensitivity to inhaled allergens” and hay fever. Logistic regressions were used, controlling for individual risk factors and study area. Heterogeneity between study-specific results, and mean effects (allowing for heterogeneity) were estimated using meta-analytical tools.Results:There was strong evidence linking parental smoking to wheeze, asthma, bronchitis and nocturnal cough, with mean odds ratios all around 1.15, with independent effects of prenatal and postnatal exposures for most associations.Conclusions:Adverse effects of both pre- and postnatal parental smoking on children’s respiratory health were confirmed. Asthma was most strongly associated with maternal smoking during pregnancy, but postnatal exposure showed independent associations with a range of other respiratory symptoms. All tobacco smoke exposure has serious consequences for children’s respiratory health and needs to be reduced urgently.
Tobacco interests or the public interest: 20 years of industry strategies to undermine airline smoking restrictions: Table 1
Authors: Lopipero Peggy , Bero Lisa A 
Published: August 2006

Objectives:To understand the evolution of 20 years of tobacco industry strategies to undermine federal restrictions of smoking on aircraft in the United States.Design:We searched and analysed internal tobacco industry records, public documents, and other related research.Results:The industry viewed these restrictions as a serious threat to the social acceptability of smoking. Its initial efforts included covert letter-writing campaigns and lobbying of the airline industry, but with the emergence of proposals to ban smoking, the tobacco companies engaged in ever increasing efforts to forestall further restrictions. Tactics to dominate the public record became especially rigorous. The industry launched an aggressive public relations campaign that began with the promotion of industry sponsored petition drives and public opinion surveys. Results from polling research that produced findings contrary to the industry’s position were suppressed. In order to demonstrate smoker outrage against a ban, later efforts included the sponsorship of smokers’ rights and other front groups. Congressional allies and industry consultants sought to discredit the science underlying proposals to ban smoking and individual tobacco companies conducted their own cabin air quality research. Faced with the potential of a ban on all domestic flights, the industry sought to intimidate an air carrier and a prominent policymaker. Despite the intensification of tactics over time, including mobilisation of an army of lobbyists and Congressional allies, the tobacco industry was ultimately defeated.Conclusions:Our longitudinal analysis provides insights into how and when the industry changed its plans and provides public health advocates with potential counterstrategies.
Mechanism regulating nuclear calcium signalingThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.
Authors: Malviya Anant N. , Klein Christian 
Published: August 2006

Although the outer nuclear membrane is continuous with the endoplasmic reticulum, it is possible to isolate nuclei both intact and free from endoplasmic reticulum contaminants. The outer and the inner nuclear membranes can be purified free from cross-contamination. Evidence in support of autonomous regulation of nuclear calcium signaling relies upon the investigations with isolated nuclei. Mechanisms for generating calcium signaling in the nucleus have been identified. Two calcium transporting systems, an ATP-dependant nuclear Ca2+-ATPase and an IP4-mediated inositol 1,3,4,5-tetrakisphosphate receptor, are located on the outer nuclear membrane. Thus, ATP and IP4, depending on external free calcium concentrations, are responsible for filling the nuclear envelope calcium pool. The inositol 1,4,5-trisphosphate receptor is located on the inner nuclear membrane with its ligand binding domain facing toward the nucleoplasm. Likewise, the ryanodine receptor is located on the inner nuclear membrane and its ligand cADP-ribose is generated within the nucleus. A 120 kDa protein fragment of nuclear PLC-γ1 is stimulated in vivo by epidermal growth factor nuclear signaling coincident with the time course of nuclear membrane epidermal growth factor receptor activation. Stimulated 120 kDa protein fragment interacts with PIKE, a nuclear GTPase, and together they form a complex with PI[3]kinase serving as a module for nuclear PI[3]K stimulation. Thus, the nucleus has its own IP3generating system.