Nuclear Localization of the Duck Hepatitis B Virus Capsid Protein: Detection and Functional Implications of Distinct Subnuclear Bodies in a Compartment Associated with RNA Synthesis and Maturation

We have reinvestigated the subcellular distribution of the duck hepatitis B virus (DHBV) core protein in infected duck hepatocytes and in transfected cells. By using indirect immunofluorescence, the protein was found to be localized not only in the cytoplasm, as described previously, but also within the cell nucleus, being concentrated in distinct, brightly staining nuclear core bodies (NCBs). In colocalization studies using confocal microscopy, the NCBs were found exclusively in the periphery of nuclear subdomains characterized as splicing factor compartments and distal to other subnuclear domains. Also relevant for their functional significance is that the NCBs formed during the establishment of virus infection, i.e., at very low overall concentrations of newly synthesized core protein, and persisted throughout all stages of infection. Moreover, a subset of NCBs colocalized with foci of pregenomic DHBV RNA present at concentrations detectable by fluorescence in situ hybridization. Taken together, these findings indicate that a minor fraction of the DHBV core protein molecules escapes the major cytoplasmic assembly pathway to accumulate in specific subnuclear domains, and they furthermore suggest that these NCBs serve a role in the synthesis and/or maturation of the DHBV RNA pregenome

Die Rolle der Spitalapotheke in klinischen Studien

Die Spitalapotheken der Kantons- und Universitätsspitäler bieten neben der Herstellung von und Versorgung des Spitals mit Arzneimitteln auch wichtige Dienstleistungen für klinische Studien an

Colicin M, a peptidoglycan lipid-II-degrading enzyme: potential use for antibacterial means?

International audienceColicins are proteins produced by some strains of Escherichia coli to kill competitors belonging to the same species. Among them, ColM (colicin M) is the only one that blocks the biosynthesis of peptidoglycan, a specific bacterial cell-wall polymer essential for cell integrity. ColM acts in the periplasm by hydrolysing the phosphoester bond of the peptidoglycan lipid intermediate (lipid II). ColM cytotoxicity is dependent on FkpA of the targeted cell, a chaperone with peptidylprolyl cis-trans isomerase activity. Dissection of ColM was used to delineate the catalytic domain and to identify the active-site residues. The in vitro activity of the isolated catalytic domain towards lipid II was 50-fold higher than that of the full-length bacteriocin. Moreover, this domain was bactericidal in the absence of FkpA under conditions that bypass the import mechanism (FhuA-TonB machinery). Thus ColM undergoes a maturation process driven by FkpA that is not required for the activity of the isolated catalytic domain. Genes encoding proteins with similarity to the catalytic domain of ColM were identified in pathogenic strains of Pseudomonas and other genera. ColM acts on several structures of lipid II representative of the diversity of peptidoglycan chemotypes. All together, these data open the way to the potential use of ColM-related bacteriocins as broad spectrum antibacterial agents

Deciphering the Catalytic Domain of Colicin M, a Peptidoglycan Lipid II-degrading Enzyme*

Colicin M inhibits Escherichia coli peptidoglycan synthesis through cleavage of its lipid-linked precursors. It has a compact structure, whereas other related toxins are organized in three independent domains, each devoted to a particular function: translocation through the outer membrane, receptor binding, and toxicity, from the N to the C termini, respectively. To establish whether colicin M displays such an organization despite its structural characteristics, protein dissection experiments were performed, which allowed us to delineate an independent toxicity domain encompassing exactly the C-terminal region conserved among colicin M-like proteins and covering about half of colicin M (residues 124–271). Surprisingly, the in vitro activity of the isolated domain was 45-fold higher than that of the full-length protein, suggesting a mechanism by which the toxicity of this domain is revealed following primary protein maturation. In vivo, the isolated toxicity domain appeared as toxic as the full-length protein under conditions where the reception and translocation steps were by-passed. Contrary to the full-length colicin M, the isolated domain did not require the presence of the periplasmic FkpA protein to be toxic under these conditions, demonstrating that FkpA is involved in the maturation process. Mutational analysis further identified five residues that are essential for cytotoxicity as well as in vitro lipid II-degrading activity: Asp-229, His-235, Asp-226, Tyr-228, and Arg-236. Most of these residues are surface-exposed and located relatively close to each other, hence suggesting they belong to the colicin M active site

Effect of intravenous TRO40303 as an adjunct to primary percutaneous coronary intervention for acute ST-elevation myocardial infarction:MITOCARE study results

The MITOCARE study evaluated the efficacy and safety of TRO40303 for the reduction of reperfusion injury in patients undergoing revascularization for ST-elevation myocardial infarction (STEMI)