MICs to β-lactams in E. coli W4573 and its acrAB mutant Selleckchem Antidiabetic Compound Library strain increased 1- to 500-fold (MIC from 0.125 to 64 μg mL−1
of aztreonam) in the blaKPC-2a, blaKPC-2b, and blaKPC-2c transformants compared with the cloning vector alone. However, transformants of the acrAB mutant strain remained susceptible to all β-lactams tested except for aztreonam and carbenicillin. Levels of the three promoters’ length and carbapenemase activities in the transformants harboring the blaKPC-2a, blaKPC-2b, and blaKPC-2c were correlated to the levels of β-lactam MICs in both E. coli W4573 and its mutant of an efflux pump (AcrAB). Overall, these results suggest that promoter-deletions of blaKPC-2 gene and AcrAB may be associated with the variability in β-lactam MICs in KPC-producing Enterobacteriaceae. “
“The nuclear ribosomal intergenic spacer (IGS) region was structurally analyzed and exploited Doxorubicin for molecular discrimination and phylogenetic analysis of vegetative compatibility groups (VCGs) of Verticillium dahliae. A structural study of 201 available IGS sequences of the fungus was performed, and four classes of ubiquitous repetitive elements, organized in higher-order repetitive structures or composite blocks, were detected in a variable
IGS subregion. This subregion was amplified from an international collection of 59 V. dahliae isolates covering all VCGs, together with nine representative V. albo-atrum and V. longisporum isolates, and sequenced. Structural and phylogenetic analyses of the sequences of this polymorphic IGS subregion were consistently informative and allowed the identification of two main lineages in V. dahliae, that is, clade I including VCGs 1A, 1B, 2A, 4B, and 3 and clade II containing
VCGs Monoiodotyrosine 2B, 4A, and 6. Analysis of IGS sequences proved a highly suitable molecular tool for (a) rapid interspecific differentiation, (b) intraspecific discrimination among VCGs of V. dahliae, facilitating high-throughput VCG confirmation and prediction/profiling, and (c) phylogenetic analysis within and among V. dahliae VCGs. “
“The isophthalate (IPA) catabolic operon (iphACBDR) of Comamonas sp. strain E6 responsible for the conversion of IPA into protocatechuate is negatively regulated by an IclR-type transcriptional regulator, IphR. Promoter analysis showed that the region sufficient for the IPA-dependent induction of the iphA promoter was located within the 87 bp region upstream from the iphA start codon. The transcription start site of the iph operon was mapped at a cytosine located 49 bp upstream of the iphA start codon. Two inverted repeat sequences IR1 (positions −21 to −7 relative to the iphA transcription start site) and IR2 (−2 to +10) were found in the binding region of IphR identified by electrophoretic mobility shift assays (EMSA) using purified IphR.