62 research outputs found

    The Abi-domain protein Abx1 interacts with the CovS histidine kinase to control virulence gene expression in group B Streptococcus

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    Group B Streptococcus (GBS), a common commensal of the female genital tract, is the leading cause of invasive infections in neonates. Expression of major GBS virulence factors, such as the hemolysin operon cyl, is regulated directly at the transcriptional level by the CovSR two-component system. Using a random genetic approach, we identified a multi-spanning transmembrane protein, Abx1, essential for the production of the GBS hemolysin. Despite its similarity to eukaryotic CaaX proteases, the Abx1 function is not involved in a post-translational modification of the GBS hemolysin. Instead, we demonstrate that Abx1 regulates transcription of several virulence genes, including those comprising the hemolysin operon, by a CovSR-dependent mechanism. By combining genetic analyses, transcriptome profiling, and site-directed mutagenesis, we showed that Abx1 is a regulator of the histidine kinase CovS. Overexpression of Abx1 is sufficient to activate virulence gene expression through CovS, overcoming the need for an additional signal. Conversely, the absence of Abx1 has the opposite effect on virulence gene expression consistent with CovS locked in a kinase-competent state. Using a bacterial two-hybrid system, direct interaction between Abx1 and CovS was mapped specifically to CovS domains involved in signal processing. We demonstrate that the CovSR two-component system is the core of a signaling pathway integrating the regulation of CovS by Abx1 in addition to the regulation of CovR by the serine/threonine kinase Stk1. In conclusion, our study reports a regulatory function for Abx1, a member of a large protein family with a characteristic Abi-domain, which forms a signaling complex with the histidine kinase CovS in GBS

    Streptococcus agalactiae clones infecting humans were selected and fixed through the extensive use of tetracycline

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    Streptococcus agalactiae (Group B Streptococcus, GBS) is a commensal of the digestive and genitourinary tracts of humans that emerged as the leading cause of bacterial neonatal infections in Europe and North America during the 1960s. Due to the lack of epidemiological and genomic data, the reasons for this emergence are unknown. Here we show by comparative genome analysis and phylogenetic reconstruction of 229 isolates that the rise of human GBS infections corresponds to the selection and worldwide dissemination of only a few clones. The parallel expansion of the clones is preceded by the insertion of integrative and conjugative elements conferring tetracycline resistance (TcR). Thus, we propose that the use of tetracycline from 1948 onwards led in humans to the complete replacement of a diverse GBS population by only few TcR clones particularly well adapted to their host, causing the observed emergence of GBS diseases in neonates. \ua9 2014 Macmillan Publishers Limited. All rights reserved

    Search for single production of vector-like quarks decaying into Wb in pp collisions at s=8\sqrt{s} = 8 TeV with the ATLAS detector

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    Measurement of the charge asymmetry in top-quark pair production in the lepton-plus-jets final state in pp collision data at s=8TeV\sqrt{s}=8\,\mathrm TeV{} with the ATLAS detector

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    Search for dark matter in association with a Higgs boson decaying to bb-quarks in pppp collisions at s=13\sqrt s=13 TeV with the ATLAS detector

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    Charged-particle distributions at low transverse momentum in s=13\sqrt{s} = 13 TeV pppp interactions measured with the ATLAS detector at the LHC

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    Measurement of the bbb\overline{b} dijet cross section in pp collisions at s=7\sqrt{s} = 7 TeV with the ATLAS detector

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    ATLAS Run 1 searches for direct pair production of third-generation squarks at the Large Hadron Collider

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    Les mères et la mort: réalités et représentations

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    NTNU Vitenskapsmuseet arkeologisk rapport 2018:2. Arkeologisk undersøkelse, Gjemnes, Møre og Romsdal

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    I forbindelse med tilskudd til drenering av landbruksareal på gnr. 48/2 på Bergsøy i Gjemnes kommune, Møre og Romsdal fylke, foretok NTNU Vitenskapsmuseet sommeren 2017 arkeologiske utgravinger av to lokaliteter, lokalitet 1 (Askeladden ID 35620) og lokalitet 2 (Askeladden ID 214024). Begge lokalitetene lå på mark som ble brukt som beitemark, men som før hadde vært oppdyrket. Lokalitet 1 hadde mest spor fra senmesolittisk aktivitet, men hadde også spor fra andre perioder. Det ble her funnet 2610 funn, hvorav alle var fra eldre steinalder. Lokalitet 2 hadde mest spor fra neolittisk tid og vikingtid, og herfra ble det gjort 384 funn. Det ble målt inn 27 strukturer på begge lokalitetene, der de alle fleste var grøfter, men det var også et par rydningsrøyser, en vikingtids kokegrop og en neolittisk kokegrop/avfallsgrop. På lokalitet 1 fantes det et senmesolittisk kulturlag med en grop som kan tolkes som en tuft, men uten karakteristika som veggvoller, grøfter, stolpehull etc. som kan støtte en slik tolkning. På lokalitet 2 fantes det dype dyrkningslag, der de eldste ser ut til å stamme fra merovingertid/vikingtid. Det ble sendt inn 17 prøver til datering der tidsspennet gikk fra senmesolittikum til vikingtid, som støttet opp de fleste antagelsene om datering som var gjort i felt, ved hjelp av strandlinjedatering og gjenstandsdatering. Den menneskelige aktiviteten på lokalitetene har begynt når områdene kom opp fra havet, og har vært mer og mindre aktivt fram til i dag. Det kan virke som husdyrhold kan ha kommet inn i senneolittikum, og den moderne gården kan ha kommet til i sen merovingertid/tidlig vikingtid
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