Pseudomonas aeruginosa is one of the most dreaded Gram-negative bacterial pathogens in hospitals. Not only it is among the most frequently isolated Gram-negative organisms in bloodstream and wound ...infections, pneumonia, intra-abdominal-sepsis and urogenital-sepsis, but also it is frequently found in patients with comorbid illnesses and compromised by in-dwelling catheters, tubes and surgery where mortality rates of more than 60% have been reported. Besides its intrinsic resistance to a number of widely used antibiotics, Pseudomonas also managed to acquire resistance via additional mechanisms, including target mutations, increased expression of efflux pumps and of antibiotic-degrading enzymes. Taken together, the increased incidence in certain types of infections, the increased use of invasive devices in the hospital as well as the increased frequency of multi-resistant Pseudomonas strains, have clearly led to a shortage of treatment options for nosocomial Pseudomonas infections. Even the recommended combination therapy of an antibiotic of the β-lactam class together with an aminoglycoside or a fluoroquinolone, is no longer always successful and sometimes a polymyxin has to be given as last resort. Despite growing concerns of clinicians and medical societies about the very limited number of novel drugs in the pipeline to fight multi-resistant Pseudomonas strains, only a very small number of novel anti- Pseudomonas drugs are currently in late stage of pre-clinical or clinical development. However, and possibly as a reflection of the magnitude of the problem, quite a variety of approaches are being pursued. Among these are next-generation analogues of successful antibiotic classes (e.g. novel β-lactams and combinations of novel β-lactamase inhibitors with known penicillins or cephalosporins), antibodies, phages and selective peptides. It is to be hoped that a number of these novel drugs will show clinical utility and reach the market over the next 6–10 years.
A new cDNA encoding a protein of 362 amino acids designated SH3GLB1, for SH3 domain GRB2-like endophilin B1, was identified in a yeast two-hybrid screen devoted to the identification of new partners ...interacting with the apoptosis inducer Bax. SH3GLB1 shows strong similarities to the SH3 domain-containing proteins of the endophilin family and presumably represents the human homologue of the potential Caenorhabditis elegans SH3 containing-protein identified by systematic translation of the C. elegans genome (GenBank Accession No. U46675). Reversing prey to bait in the yeast screen, a second protein, SH3GLB2, of 395 amino acids showing65% identity to SH3GLB1 was identified as an interactingpartner of SH3GLB1. The discovery of SH3GLB1 itself in the screening with SH3GLB1 as a bait and further mapping experiments demonstrated that a core coiled-coil-type region isrequired for the formation of SH3GLB homo- and/orheterodimers, whereas the SH3 domain is not involved in these interactions. Interestingly, the similarities with the endophilin proteins cover the entire sequence of the SH3GLB family, suggesting a common fold and presumably a common mode of action. Furthermore, SH3GLB members colocalize to the cytoplasmic compartment of the cell together with Bax and are excluded from the nucleus.SH3GLB1 and SH3GLB2 do not significantly influence the onset and time course of Bax-mediated apoptosis in HeLa or 293T cells.
Second-site NMR screening and linker design Jahnke, Wolfgang; Flörsheimer, Andreas; Blommers, Marcel J J ...
Current topics in medicinal chemistry,
2003, Letnik:
3, Številka:
1
Journal Article
Recenzirano
One of the prime merits of NMR as a tool for lead finding in drug discovery research is its sensitivity and robustness to detect weak protein-ligand interactions. This sensitivity allows to build up ...ligands for a given target in a modular way, by a fragment-based approach. In this approach, two ligands are seperately identified which bind to the target protein generally weakly, but at adjacent binding sites. In a next step, they are chemically linked to produce a high-affinity ligand. This review discusses methods to detect "second-site" ligands that bind to a protein in the presence of a "first-site" ligand, and methods to elucidate structural details on the spatial orientation of both ligands, so that chemical linkage is based on a large piece of experimental information. Published examples from second-site screening and linker design are summarized, and are complemented by previously unpublished in-house examples.
BFL-1 is the smallest member of the BCL-2 family and has been shown to retard apoptosis in various cell lines. However, the structural basis for its function remains unclear. Molecular modeling ...showed that BFL-1 could have a similar core structure as BCL-xL, consisting of seven α helices, although both proteins share only the conserved BCL-2 homology domains (BH1 and BH2 domains), but otherwise have very limited sequence homology, particularly in the N-terminal region. We demonstrated in the yeast two-hybrid system that BFL-1 interacts strongly with human BAX but is not able to form homodimers nor to interact with human BCL-2 or BCL-xL. Overexpression experiments in REF52 rat fibroblasts showed that BFL-1 conferred increased resistance to apoptosis induced by serum deprivation. BFL-1 had also the ability to neutralize BAX lethality in yeast. BAX requires the BH3 domain for interaction with BFL-1. However, the minimal region of BFL-1 for the interaction with BAX in coimmunoprecipitation experiments was not sufficient to protect cells from apoptosis. Further examination of BFL-1 and several other anti-apoptotic proteins suggests a more general type of structure based on structural motifs,i.e. a hydrophobic pocket for the binding of proapoptotic proteins, rather than extended sequence homologies.
It is known that overexpression of Bax accelerates apoptosis, but the biochemical mechanism of the signal transduction from Bax to downstream targets has still not been fully determined. In the ...present study, we demonstrate that upon apoptotic stimuli, Bax moves from the cytosolic to the membrane fraction. The redistribution of Bax is not inhibited by a caspase inhibitor, zVAD-fmk, which blocks caspase-3 activity and prevents apoptosisin vivo.A FL5.12 Bax CL16 mutant cell, ms3, which is resistant to apoptosis induced by staurosporine, retains the activity of Bax redistribution but shows no caspase-3 activity. Our results revealed that Bax accumulation on membranes precedes caspase-3 activation, indicating that redistribution of Bax is an early event in apoptosis. These results suggest that Bax may be functionally significant in the regulation of caspase-3 activation.
DNA microarrays are powerful tools for the analysis of gene expression on a genomic scale. The importance of individual regulatory events for the process under study can however not be deduced ...unequivocally without additional experiments. We devised a strategy to identify central regulators of cancer drug responses by combining the results of microarray experiments with efficient methods for phenotypic testing of candidate genes. We exposed murine FL5.12 pro-B cells to cisplatin, camptothecin, methotrexate or paclitaxel, respectively and analysed the patterns of gene expression with cDNA microarrays. Drug-specific regulatory events as well as intersections between different apoptotic pathways, including previously studied responses to staurosporine and interleukin-3 (IL-3) deprivation, were identified. Genes shared by at least three pathways were chosen for further analysis. Ectopic expression of three such genes, TEAP, GP49B, and Lipin1 was found to have an anti-proliferative effect on pro-B cells. Interestingly, we identified hemoglobin alpha as a strong pro-apoptotic regulator. While hemoglobin-expressing cells were growing normally in the presence of IL-3, they displayed accelerated apoptosis with similar kinetics as Bax overexpressing cells upon IL-3 removal. The pro-apoptotic effect of hemoglobin was suppressed by Bcl-2 and was characterized by enhanced stimulation of caspase activity.
Abstract Candida parapsilosis is globally distributed and recognised for causing an increasing proportion of invasive Candida infections. It is associated with high crude mortality in all age groups. ...It has been particularly associated with nosocomial outbreaks, particularly in association with the use of invasive medical devices such as central venous catheters. Candida parapsilosis is one of the pathogens considered in the WHO priority pathogens list, and this review was conducted to inform the ranking of the pathogen in the list. In this systematic review, we searched PubMed and Web of Science to find studies between 2011 and 2021 reporting on the following criteria for C. parapsilosis infections: mortality, morbidity (hospitalisation and disability), drug resistance, preventability, yearly incidence, and distribution/emergence. We identified 336 potentially relevant papers, of which 51 were included in the analyses. The included studies confirmed high mortality rates, ranging from 17.5% to 46.8%. Data on disability and sequelae were sparse. Many reports highlighted concerns with azole resistance, with resistance rates of >10% described in some regions. Annual incidence rates were relatively poorly described, although there was clear evidence that the proportion of candidaemia cases caused by C. parapsilosis increased over time. While this review summarises current data on C.parapsilosis, there remains an urgent need for ongoing research and surveillance to fully understand and manage this increasingly important pathogen.
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