Faced with the global health threat of increasing resistance to antibiotics, researchers are exploring interventions that target bacterial virulence factors. Quorum sensing is a particularly attractive target because several bacterial virulence factors are controlled by this mechanism. Furthermore, attacking the quorum-sensing signaling network is less likely to select for resistant strains than using conventional antibiotics. Strategies that focus on the inhibition of quorum-sensing signal production are especially attractive because the enzymes involved are expressed in bacterial cells but are not present in their mammalian counterparts. We review here various approaches that are being taken to interfere with quorum-sensing signal production via the inhibition of autoinducer-2 synthesis, PQS synthesis, peptide autoinducer synthesis, and N-acyl-homoserine lactone synthesis. We expect these approaches will lead to the discovery of new quorum-sensing inhibitors that can help to stem the tide of antibiotic resistance.

Mutations in the growth hormone receptor (GHR) gene can cause disruption of the growth hormone signaling pathway, resulting in growth deficiency due to growth hormone (GH) resistance. Both recessive and apparently dominant mutations have been described in the literature. In order to shed some light on the molecular mechanism of partial growth hormone resistance caused by heterozygous mutations, we performed an in-depth in silico analysis of a mutation found in a girl with a previous diagnosis of idiopathic short stature. An array of algorithms was used to predict pathogenicity and potential impact on the protein, and molecular modeling, docking and dynamics were used to determine structural consequences. The results suggest that both of the possible single mutation-containing heteromeric GH-GHR complexes, as well as the double GHR mutant complex result in perturbation of complex structures, with altered ability of the GHR dimers to interact with the GH peptide. J. Cell. Biochem. 118: 4762-4771, 2017. © 2017 Wiley Periodicals, Inc.

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Pseudomonas aeruginosa (P. aeruginosa) produces a suite of virulence factors that are coordinated by Quorum Sensing (QS) contributing to its disease-causing ability in aquaculture. The present study is first of its kind to obtain information regarding the presence and distribution of five QS genes, three virulence genes viz: lasI, lasR, rhlI, rhlR, rhlAB, toxA, aprA and plcH and seven of the Extended-spectrum βlactamases (blaVEB, blaPER, blaTEM,, blaSHV, blaCTX-M1, blaCTX-M2 and blaCTX-M3) of Pseudomonas species isolated from fish meat by direct PCR. Bacterial identification was based mainly on conventional biochemical techniques using the Vitek 2, automated system. Phenotypic sensitivity of antibiotics was established by the agar disc diffusion technique through 16 various antimicrobial drugs. Quantification of their in vitro production of numerous virulence genes outside the cell that are QS dependent namely, pyocyanin, elastase, alkaline protease, biofilm and cytotoxicity of Vero cell was as well executed. Fifteen genes demonstrated an enormous variety in their association. The total number of Pseudomonas species isolates were 30/100 to be identified by the API 20NE system as P. aeruginosa 12/30 (40%), P. fluorescens 8/30 (27%), P. putida 6/30 (20%) and P. alkylphenolia 4/30 (13%). The outcomes of this study have great significance for the strategic designation of QS quenching.