Towards the sustainable discovery and development of new antibiotics.

An ever-increasing demand for novel antimicrobials to treat life-threatening infections caused by the global spread of multidrug-resistant bacterial pathogens stands in stark contrast to the current level of investment in their development, particularly in the fields of natural-product-derived and synthetic small molecules. New agents displaying innovative chemistry and modes of action are desperately needed worldwide to tackle the public health menace posed by antimicrobial resistance. Here, our consortium presents a strategic blueprint to substantially improve our ability to discover and develop new antibiotics.

Towards the sustainable discovery and development of new antibiotics.

An ever-increasing demand for novel antimicrobials to treat life-threatening infections caused by the global spread of multidrug-resistant bacterial pathogens stands in stark contrast to the current level of investment in their development, particularly in the fields of natural-product-derived and synthetic small molecules. New agents displaying innovative chemistry and modes of action are desperately needed worldwide to tackle the public health menace posed by antimicrobial resistance. Here, our consortium presents a strategic blueprint to substantially improve our ability to discover and develop new antibiotics.

Identification of Novel Chemical Scaffolds Inhibiting Trypanothione Synthetase from Pathogenic Trypanosomatids.

Background: The search for novel chemical entities targeting essential and parasite-specific pathways is considered a priority for neglected diseases such as trypanosomiasis and leishmaniasis. The thiol-dependent redox metabolism of trypanosomatids relies on bis-glutathionylspermidine [trypanothione, T(SH)2], a low molecular mass cosubstrate absent in the host. In pathogenic trypanosomatids, a single enzyme, trypanothione synthetase (TryS), catalyzes trypanothione biosynthesis, which is indispensable for parasite survival.

Genetic and chemical analyses reveal that trypanothione synthetase but not glutathionylspermidine synthetase is essential for Leishmania infantum.

Trypanothione is a unique and essential redox metabolite of trypanosomatid parasites, the biosynthetic pathway of which is regarded as a promising target for antiparasitic drugs. Synthesis of trypanothione occurs by the consecutive conjugation of two glutathione molecules to spermidine. Both reaction steps are catalyzed by trypanothione synthetase (TRYS), a molecule known to be essential in Trypanosoma brucei.

A fast virtual screening approach to identify structurally diverse inhibitors of trypanothione reductase.

Trypanothione reductase (TryR) is one of the favorite targets for those designing drugs for the treatment of Chagas disease. We present the application of a fast virtual screening approach for designing hit compounds active against TryR. Our protocol combines information derived from structurally known inhibitors and from the TryR receptor structure.

Use of small angle neutron scattering to study the interaction of angiotensin II with model membranes.

Understanding biological processes assumes a detailed understanding of the interaction of all involved molecules. Here the effect of the peptide hormone angiotensin II (Ang II), an agonist of the angiotensin receptors, on the structure of unilamellar and multilamellar dimyristoyl phosphatidylcholine vesicles was studied by small angle neutron scattering, dynamic light scattering and differential scanning calorimetry. The calorimetry data indicate a weak interaction of Ang II with the surface of the membrane bilayer, as the pretransition persists during all experiments, and the main transition is only slightly shifted towards higher temperatures.

Thiol peroxidase protects Salmonella enterica from hydrogen peroxide stress in vitro and facilitates intracellular growth.

At present, Salmonella is considered to express two peroxiredoxin-type peroxidases, TsaA and AhpC. Here we describe an additional peroxiredoxin, Tpx, in Salmonella enterica and show that a single tpx mutant is susceptible to exogenous hydrogen peroxide (H(2)O(2)), that it has a reduced capacity to degrade H(2)O(2) compared to the ahpCF and tsaA mutants, and that its growth is affected in activated macrophages. These results suggest that Tpx contributes significantly to the sophisticated defense system that the pathogen has evolved to survive oxidative stress.

Peroxiredoxin systems in mycobacteria.

Like other actinomycetes Mycobacterium tuberculosis lacks glutathione and, consequently, the glutathione peroxidases that dominate the antioxidant defence of its mammalian hosts. The hydrogen peroxide metabolism of the pathogen has for long been recognised to depend on a heme-containing catalase/peroxidase. Clinical isolates lacking the catalase were virulent and proved to be resistant to the first line tuberculostatic isoniazid, because the enzyme is evidently required to activate this drug.

The thiol-based redox networks of pathogens: unexploited targets in the search for new drugs.

Hydroperoxide metabolism in diverse pathogens is reviewed under consideration of involved enzymes as potential drug targets. The common denominator of the peroxidase systems of Trypanosoma, Leishmania, Plasmodium, and Mycobacterium species is the use of NAD(P)H to reduce hydroperoxides including peroxynitrite via a flavin-containing disulfide reductase, a thioredoxin (Trx)-related protein and a peroxidase that operates with thiol catalysis. In Plasmodium falciparum, thioredoxin- and glutathione dependent systems appear to be linked via glutaredoxin and plasmoredoxin to terminal thioredoxin peroxidases belonging to both, the peroxiredoxin (Prx) and glutathione peroxidase (GPx) family.

The mycobacterial thioredoxin peroxidase can act as a one-cysteine peroxiredoxin.

Thioredoxin peroxidase (TPx) has been reported to dominate the defense against H(2)O(2), other hydroperoxides, and peroxynitrite at the expense of thioredoxin (Trx) B and C in Mycobacterium tuberculosis (Mt). By homology, the enzyme has been classified as an atypical 2-C-peroxiredoxin (Prx), with Cys(60) as the "peroxidatic" cysteine (C(P)) forming a complex catalytic center with Cys(93) as the "resolving" cysteine (C(R)). Site-directed mutagenesis confirms Cys(60) to be C(P) and Cys(80) to be catalytically irrelevant.

Multiple thioredoxin-mediated routes to detoxify hydroperoxides in Mycobacterium tuberculosis.

Drug resistance and virulence of Mycobacterium tuberculosis are in part related to the pathogen's antioxidant defense systems. KatG(-) strains are resistant to the first line tuberculostatic isoniazid but need to compensate their catalase deficiency by alternative peroxidase systems to stay virulent. So far, only NADH-driven and AhpD-mediated hydroperoxide reduction by AhpC has been implicated as such virulence-determining mechanism.