Recursos de colección

ARCA - Access to Research and Communication Annals - IGC Repository (649 recursos)

The Institutional Repository of Instituto Gulbenkian de Ciência, developed under the project RCAAP, is intended to collect, preserve and promote open access to the intellectual production of their researchers.

Bacterial Signalling

Mostrando recursos 1 - 7 de 7

  1. Manipulation of the Quorum Sensing Signal AI-2 Affects the Antibiotic-Treated Gut Microbiota

    Thompson, Jessica Ann; Oliveira, Rita Almeida; Djukovic, Ana; Ubeda, Carles; Xavier, Karina Bivar
    The uploaded pdf article contains attached the supplementary files.

  2. Signal Integration in Quorum Sensing Enables Cross-Species Induction of Virulence in Pectobacterium wasabiae

    Valente, Rita S.; Nadal-Jimenez, Pol; Carvalho, André F. P.; Vieira, Filipe J. D.; Xavier, Karina B.
    This deposit is composed by the main article plus the supplementary materials of the publication.

  3. A Mutational Hotspot and Strong Selection Contribute to the Order of Mutations Selected for during Escherichia coli Adaptation to the Gut

    Lourenço, Marta; Ramiro, Ricardo S; Güleresi, Daniela; Barroso-Batista, João; Xavier, Karina B; Gordo, Isabel; Sousa, Ana
    The relative role of drift versus selection underlying the evolution of bacterial species within the gut microbiota remains poorly understood. The large sizes of bacterial populations in this environment suggest that even adaptive mutations with weak effects, thought to be the most frequently occurring, could substantially contribute to a rapid pace of evolutionary change in the gut. We followed the emergence of intra-species diversity in a commensal Escherichia coli strain that previously acquired an adaptive mutation with strong effect during one week of colonization of the mouse gut. Following this first step, which consisted of inactivating a metabolic operon, one...

  4. The Trk Potassium Transporter Is Required for RsmB-Mediated Activation of Virulence in the Phytopathogen Pectobacterium wasabiae

    Valente, Rita S.; Xavier, Karina B.
    Pectobacterium wasabiae (previously known as Erwinia carotovora) is an important plant pathogen that regulates the production of plant cell wall-degrading enzymes through an N-acyl homoserine lactone-based quorum sensing system and through the GacS/GacA two-component system (also known as ExpS/ExpA). At high cell density, activation of GacS/GacA induces the expression of RsmB, a noncoding RNA that is essential for the activation of virulence in this bacterium. A genetic screen to identify regulators of RsmB revealed that mutants defective in components of a putative Trk potassium transporter (trkH and trkA) had decreased rsmB expression. Further analysis of these mutants showed that changes...

  5. The Multiple Signaling Systems Regulating Virulence in Pseudomonas aeruginosa

    Nadal Jimenez, P.; Koch, G.; Thompson, J. A.; Xavier, K. B.; Cool, R. H.; Quax, W. J.
    Cell-to-cell communication is a major process that allows bacteria to sense and coordinately react to the fluctuating conditions of the surrounding environment. In several pathogens, this process triggers the production of virulence factors and/or a switch in bacterial lifestyle that is a major determining factor in the outcome and severity of the infection. Understanding how bacteria control these signaling systems is crucial to the development of novel antimicrobial agents capable of reducing virulence while allowing the immune system of the host to clear bacterial infection, an approach likely to reduce the selective pressures for development of resistance. We provide here...

  6. Positive Epistasis Drives the Acquisition of Multidrug Resistance

    Trindade, S.; Sousa, A.; Xavier, KB.; Dionisio, F.; Ferreira, MG.; Gordo, I.
    The evolution of multiple antibiotic resistance is an increasing global problem. Resistance mutations are known to impair fitness, and the evolution of resistance to multiple drugs depends both on their costs individually and on how they interact-epistasis. Information on the level of epistasis between antibiotic resistance mutations is of key importance to understanding epistasis amongst deleterious alleles, a key theoretical question, and to improving public health measures. Here we show that in an antibiotic-free environment the cost of multiple resistance is smaller than expected, a signature of pervasive positive epistasis among alleles that confer resistance to antibiotics. Competition assays reveal...

  7. The crystal structure of the Escherichia coli autoinducer-2 processing protein protein LsrF

    Diaz, Z.; Xavier, KB.; Miller, ST.
    Many bacteria produce and respond to the quorum sensing signal autoinducer-2 (AI-2). Escherichia coli and Salmonella typhimurium are among the species with the lsr operon, an operon containing AI-2 transport and processing genes that are up regulated in response to AI-2. One of the Lsr proteins, LsrF, has been implicated in processing the phosphorylated form of AI-2. Here, we present the structure of LsrF, unliganded and in complex with two phospho-AI-2 analogues, ribose-5-phosphate and ribulose-5-phosphate. The crystal structure shows that LsrF is a decamer of (alpha beta)(8)-barrels that exhibit a previously unseen N-terminal domain swap and have high structural homology...

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