Mostrando recursos 1 - 2 de 2

  1. 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...
    - 08-jul-2016

  2. 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...
    - 08-jul-2016

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