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Auto Tag: Osaka University

July 7, 2019  |  

Whole-genome sequence of Streptococcus tigurinus strain osk_001, isolated from postmortem material.

Streptococcus tigurinus was recently described as a novel species, and some strains are highly virulent. We detected S. tigurinus in infected tissue sampled by necropsy. In order to characterize and confirm the virulence of this species, whole-genome sequencing of the pure cultured bacterium was performed. We found that the strain has specific and unique genetic elements contained in highly virulent strains of S. tigurinus. Copyright © 2017 Yoshizawa et al.

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July 7, 2019  |  

Genetic characterization of blaNDM-harboring plasmids in carbapenem-resistant Escherichia coli from Myanmar.

The bacterial enzyme New Delhi metallo-ß-lactamase hydrolyzes almost all ß-lactam antibiotics, including carbapenems, which are drugs of last resort for severe bacterial infections. The spread of carbapenem-resistant Enterobacteriaceae that carry the New Delhi metallo-ß-lactamase gene, blaNDM, poses a serious threat to public health. In this study, we genetically characterized eight carbapenem-resistant Escherichia coli isolates from a tertiary care hospital in Yangon, Myanmar. The eight isolates belonged to five multilocus-sequence types and harbored multiple antimicrobial-resistance genes, resulting in resistance against nearly all of the antimicrobial agents tested, except colistin and fosfomycin. Nine plasmids harboring blaNDM genes were identified from these isolates. Multiple blaNDM genes were found in the distinct Inc-replicon types of the following plasmids: an IncA/C2 plasmid harboring blaNDM-1 (n = 1), IncX3 plasmids harboring blaNDM-4 (n = 2) or blaNDM-7 (n = 1), IncFII plasmids harboring blaNDM-4 (n = 1) or blaNDM-5 (n = 3), and a multireplicon F plasmid harboring blaNDM-5 (n = 1). Comparative analysis highlighted the diversity of the blaNDM-harboring plasmids and their distinct characteristics, which depended on plasmid replicon types. The results indicate circulation of phylogenetically distinct strains of carbapenem-resistant E. coli with various plasmids harboring blaNDM genes in the hospital.

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July 7, 2019  |  

Crystal structures of the TRIC trimeric intracellular cation channel orthologues.

Ca(2+) release from the sarcoplasmic reticulum (SR) and endoplasmic reticulum (ER) is crucial for muscle contraction, cell growth, apoptosis, learning and memory. The trimeric intracellular cation (TRIC) channels were recently identified as cation channels balancing the SR and ER membrane potentials, and are implicated in Ca(2+) signaling and homeostasis. Here we present the crystal structures of prokaryotic TRIC channels in the closed state and structure-based functional analyses of prokaryotic and eukaryotic TRIC channels. Each trimer subunit consists of seven transmembrane (TM) helices with two inverted repeated regions. The electrophysiological, biochemical and biophysical analyses revealed that TRIC channels possess an ion-conducting pore within each subunit, and that the trimer formation contributes to the stability of the protein. The symmetrically related TM2 and TM5 helices are kinked at the conserved glycine clusters, and these kinks are important for the channel activity. Furthermore, the kinks of the TM2 and TM5 helices generate lateral fenestrations at each subunit interface. Unexpectedly, these lateral fenestrations are occupied with lipid molecules. This study provides the structural and functional framework for the molecular mechanism of this ion channel superfamily.

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July 7, 2019  |  

TeloPCR-seq: a high-throughput sequencing approach for telomeres.

We have developed a high-throughput sequencing approach that enables us to determine terminal telomere sequences from tens of thousands of individual Schizosaccharomyces pombe telomeres. This method provides unprecedented coverage of telomeric sequence complexity in fission yeast. S. pombe telomeres are composed of modular degenerate repeats that can be explained by variation in usage of the TER1 RNA template during reverse transcription. Taking advantage of this deep sequencing approach, we find that ‘like’ repeat modules are highly correlated within individual telomeres. Moreover, repeat module preference varies with telomere length, suggesting that existing repeats promote the incorporation of like repeats and/or that specific conformations of the telomerase holoenzyme efficiently and/or processively add repeats of like nature. After the loss of telomerase activity, this sequencing and analysis pipeline defines a population of telomeres with altered sequence content. This approach will be adaptable to study telomeric repeats in other organisms and also to interrogate repetitive sequences throughout the genome that are inaccessible to other sequencing methods.© 2016 Federation of European Biochemical Societies.

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