Substrate-derived Sortase A inhibitors: targeting an essential virulence factor of Gram-positive pathogenic bacteria

The bacterial transpeptidase Sortase A (SrtA) is a surface enzyme of Gram-positive pathogenic bacteria. It has been shown to be an essential virulence factor for the establishment of various bacterial infections, including septic arthritis. However, the development of potent Sortase A inhibitors remains an unmet challenge. Sortase A relies on a five amino acid sorting signal (LPXTG), by which it recognizes its natural target. We report the synthesis of a series of peptidomimetic inhibitors of Sortase A based on the sorting signal, supported by computational binding analysis. By employing a FRET-compatible substrate, our inhibitors were assayed in vitro. Among our panel, we identified several promising inhibitors with IC50 values below 200 mu M, with our strongest inhibitor - LPRDSar - having an IC50 of 18.9 mu M. Furthermore, it was discovered that three of our compounds show an effect on growth and biofilm inhibition of pathogenic Staphylococcus aureus, with the inclusion of a phenyl ring seemingly key to this effect. The most promising compound in our panel, BzLPRDSar, could inhibit biofilm formation at concentrations as low as 32 mu g mL(-1), manifesting it as a potential future drug lead. This could lead to treatments for MRSA infections in clinics and diseases such as septic arthritis, which has been directly linked with SrtA

Protein cohabitation: long-term immunoglobulin G storage at room temperature

Long-term functional storage of therapeutic proteins at room temperature has been an eternal challenge. Inspired by the cellular cooperativity of proteins, we have taken a step forward to address this challenge by cohabitating Immunoglobulin G (IgG1) with a food protein gelatin in the solid-state at room temperature. Interestingly, IgG1 remained functionally active for a record 14 months revealed from the western-blot assay. Further quantification by HP-LC analysis showed 100% structural integrity of IgG1 with no degradation in the gelatin matrix during this period. The developed formulation has a direct application in oral medical nutrition therapy to cure gastrointestinal microbial infections. Also the strategy provides a robust energy economic alternative to the protein engineering methods for long-term functional storage of therapeutic proteins at room temperature

Bottleneck size and selection level reproducibly impact evolution of antibiotic resistance

During antibiotic treatment, the evolution of bacterial pathogens is fundamentally affected by bottlenecks and varying selection levels imposed by the drugs. Bottlenecks—that is, reductions in bacterial population size—lead to an increased influence of random effects (genetic drift) during bacterial evolution, and varying antibiotic concentrations during treatment may favour distinct resistance variants. Both aspects influence the process of bacterial evolution during antibiotic therapy and thereby treatment outcome. Surprisingly, the joint influence of these interconnected factors on the evolution of antibiotic resistance remains largely unexplored. Here we combine evolution experiments with genomic and genetic analyses to demonstrate that bottleneck size and antibiotic-induced selection reproducibly impact the evolutionary path to resistance in pathogenic Pseudomonas aeruginosa, one of the most problematic opportunistic human pathogens. Resistance is favoured—expectedly—under high antibiotic selection and weak bottlenecks, but—unexpectedly—also under low antibiotic selection and severe bottlenecks. The latter is likely to result from a reduced probability of losing favourable variants through drift under weak selection. Moreover, the absence of high resistance under low selection and weak bottlenecks is caused by the spread of low-resistance variants with high competitive fitness under these conditions. We conclude that bottlenecks, in combination with drug-induced selection, are currently neglected key determinants of pathogen evolution and outcome of antibiotic treatment

The Systemic Management of Advanced Melanoma in 2016

Melanoma is a common type of skin cancer with a high propensity to metastasize. Tyrosine kinase inhibitors targeting the mitogen-activated protein kinase (MAPK) pathway and immune checkpoint blockade have recently revolutionized the management of unresectable and metastatic disease. However, acquired resistance and primary non-response to therapy require novel treatment strategies and combinations. The purpose of this review is to provide a brief and up-to-date overview on the clinical management and current trial landscape in melanoma. We summarize the most pertinent studies on BRAF/MEK inhibitors and blockade of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1). Although most agents show robust antitumor efficacy as single agents, further improvements have been achieved by the combination of both approved and developing drugs. We discuss ongoing trials and evaluate future approaches that may provide additional efficacy with less toxicity. (C) 2016 S. Karger GmbH, Freibur

A Question of Choice

Women's reproductive rights, reproductive health, and constitutional privacy rights in the United States are addressed in light of the contemporary onslaught of the Christian Right. The misuse of State power by fundamentalist social forces in America is critiqued. The article also briefly reviews the question of State control over women's bodies

Atropselective syntheses of (-) and (+) rugulotrosin A utilizing point-to-axial chirality transfer

Chiral, dimeric natural products containing complex structures and interesting biological properties have inspired chemists and biologists for decades. A seven-step total synthesis of the axially chiral, dimeric tetrahydroxanthone natural product rugulotrosin A is described. The synthesis employs a one-pot Suzuki coupling/dimerization to generate the requisite 2,2'-biaryl linkage. Highly selective point-to-axial chirality transfer was achieved using palladium catalysis with achiral phosphine ligands. Single X-ray crystal diffraction data were obtained to confirm both the atropisomeric configuration and absolute stereochemistry of rugulotrosin A. Computational studies are described to rationalize the atropselectivity observed in the key dimerization step. Comparison of the crude fungal extract with synthetic rugulotrosin A and its atropisomer verified that nature generates a single atropisomer of the natural product.P50 GM067041 - NIGMS NIH HHS; R01 GM099920 - NIGMS NIH HHS; GM-067041 - NIGMS NIH HHS; GM-099920 - NIGMS NIH HH