Five carbapenem-resistant Acinetobacter baumannii isolates, collected from the United Arab Emirates in 2006, were investigated to identify the mechanism(s) responsible for carbapenem resistance. ...Genotyping was performed by pulsed-field gel electrophoresis, and the location of the blaOXA-23 gene was determined by using the endonuclease I CeuI technique and mating-out assays. The four isolates in which the blaOXA-23 gene was located on the chromosome within a Tn2006 composite transposon were clonally related. The single nonclonally related isolate harboured the blaOXA-23 gene on a 70-kb transferable plasmid. This study provides the first description of the dissemination of carbapenem-resistant A. baumannii isolates carrying Tn2006 on their chromosome. It is also the first report of OXA-23-producing A. baumannii isolates in the Middle East.
Granuloma annulare: an atypical site Badaoui, A; Mugnier, P; Vignon Penamen, M-D
Annales de dermatologie et de vénéréologie,
12/2014, Letnik:
141, Številka:
12
Journal Article
Carbapenem resistance in Acinetobacter baumannii is now increasingly reported. The most prevalent mechanism of carbapenem resistance in A. baumannii corresponds to the production of acquired ...carbapenem-hydrolysing class D beta-lactamases (CHDLs) encoded by blaOXA-23-like, blaOXA-40-like or blaOXA-58-like genes. Whereas the blaOXA-40 gene has been detected in Portugal, Spain and the USA, blaOXA-23 and blaOXA-58 genes have disseminated worldwide.
The release factor eRF1 terminates protein biosynthesis by recognizing stop codons at the A site of the ribosome and stimulating peptidyl-tRNA bond hydrolysis at the peptidyl transferase center. The ...crystal structure of human eRF1 to 2.8 Å resolution, combined with mutagenesis analyses of the universal GGQ motif, reveals the molecular mechanism of release factor activity. The overall shape and dimensions of eRF1 resemble a tRNA molecule with domains 1, 2, and 3 of eRF1 corresponding to the anticodon loop, aminoacyl acceptor stem, and T stem of a tRNA molecule, respectively. The position of the essential GGQ motif at an exposed tip of domain 2 suggests that the Gln residue coordinates a water molecule to mediate the hydrolytic activity at the peptidyl transferase center. A conserved groove on domain 1, 80 Å from the GGQ motif, is proposed to form the codon recognition site.
In July 2012, as the four ground-based gamma-ray telescopes of the H.E.S.S. (High Energy Stereoscopic System) array reached their tenth year of operation in Khomas Highlands, Namibia, a fifth ...telescope took its first data as part of the system. This new Cherenkov detector, comprising a 614.5m2 reflector with a highly pixelized camera in its focal plane, improves the sensitivity of the current array by a factor two and extends its energy domain down to a few tens of GeV.
The present part I of the paper gives a detailed description of the fifth H.E.S.S. telescope׳s camera, presenting the details of both the hardware and the software, emphasizing the main improvements as compared to previous H.E.S.S. camera technology.
A clinical Pseudomonas aeruginosa strain, PAe391, was found to be resistant to a number of antibiotics including ticarcillin, piperacillin, cefsulodin and amikacin, and a disk diffusion assay showed ...evidence of pronounced synergy between imipenem and various beta-lactam antibiotics. Cloning and nucleotide sequence analysis revealed the dicistronic arrangement of an aac(6')-Ib variant and a novel blaOXA-type gene between the intI and qacE delta 1 genes typical of integrons, in PAe391, this integron was apparently chromosome-borne. The beta-lactamase, named OXA-13, displayed nine amino acid changes with respect to OXA-10:I in position 10 of OXA-10 to T (I10T), G20S, D55N, N73S, T107S, Y174F, E229G, S245N and E259A, OXA-13 (pIapp = 8.0) showed poor catalytic activity against penicillins as well as cephalosporins, but was efficient in hydrolysing some penicillinase-resistant beta-lactams, such as cefotaxime and aztreonam. It was efficiently inhibited by imipenem (KIapp = 11 nM), and formed a stable complex. While the KIapp value of meropenem was similar (16 nM), the corresponding complex was less stable.
Translation termination in eukaryotes typically requires the decoding of one of three stop codons UAA, UAG or UGA by the eukaryotic release factor eRF1. The molecular mechanisms that allow eRF1 to ...decode either A or G in the second nucleotide, but to exclude UGG as a stop codon, are currently not well understood. Several models of stop codon recognition have been developed on the basis of evidence from mutagenesis studies, as well as studies on the evolutionary sequence conservation of eRF1. We show here that point mutants of Saccharomyces cerevisiae eRF1 display significant variability in their stop codon read-through phenotypes depending on the background genotype of the strain used, and that evolutionary conservation of amino acids in eRF1 is only a poor indicator of the functional importance of individual residues in translation termination. We further show that many phenotypes associated with eRF1 mutants are quantitatively unlinked with translation termination defects, suggesting that the evolutionary history of eRF1 was shaped by a complex set of molecular functions in addition to translation termination. We reassess current models of stop-codon recognition by eRF1 in the light of these new data.
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