Tolerance engineering in Deinococcus geothermalis by heterologous efflux pumps.

Producing industrially significant compounds with more environmentally friendly represents a challenging task. The large-scale production of an exogenous molecule in a host microfactory can quickly cause toxic effects, forcing the cell to inhibit production to survive. The key point to counter these toxic effects is to promote a gain of tolerance in the host, for instance, by inducing a constant flux of the neo-synthetized compound out of the producing cells.

An innovative biologic recycling process of leukoreduction filters to produce active human antimicrobial peptides.

Background: Human neutrophil peptides (HNPs) 1 to 3 are the major antimicrobial peptides of the azurophilic granules of neutrophils. They represent an important arm of the innate immune system. Their production by chemical synthesis and recombinant technologies is expensive and limited by technical constraints due to their composition and the presence of three disulfide bonds.

Montpellier Infectious Diseases (MID), 2nd annual meeting (2012).

For the second consecutive year, teams of the network "Montpellier Infectious Diseases" held their annual meeting. Whereas the 2011 meeting was focused on host-pathogen interaction and pathophysiology, the 2012 meeting was focused on the cooperation between medical and chemical sciences interdisciplinary approaches to fight against virus, bacteria and parasites. Several approaches aimed at designing new bioactive compounds were described during this meeting.

Novel AChE inhibitors for sustainable insecticide resistance management.

Resistance to insecticides has become a critical issue in pest management and it is particularly chronic in the control of human disease vectors. The gravity of this situation is being exacerbated since there has not been a new insecticide class produced for over twenty years. Reasoned strategies have been developed to limit resistance spread but have proven difficult to implement in the field.

Mycobacterium tuberculosis RbpA protein is a new type of transcriptional activator that stabilizes the σ A-containing RNA polymerase holoenzyme.

RbpA is an RNA polymerase (RNAP)-binding protein whose presence increases the tolerance levels of Mycobacteria to the first-line anti-tuberculosis drug rifampicin by an unknown mechanism. Here, we show that the role of Mycobacterium tuberculosis RbpA in resistance is indirect because it does not affect the sensitivity of RNAP to rifampicin while it stimulates transcription controlled by the housekeeping σ(A)-factor. The transcription regulated by the stress-related σ(F) was not affected by RbpA.

The transcription inhibitor lipiarmycin blocks DNA fitting into the RNA polymerase catalytic site.

Worldwide spreading of drug-resistant pathogens makes mechanistic understanding of antibiotic action an urgent task. The macrocyclic antibiotic lipiarmycin (Lpm), which is under development for clinical use, inhibits bacterial RNA polymerase (RNAP) by an unknown mechanism. Using genetic and biochemical approaches, we show that Lpm targets the sigma(70) subunit region 3.

Resistance to rifampicin: at the crossroads between ecological, genomic and medical concerns.

The first antibiotic of the ansamycin family, rifampicin (RIF), was isolated in 1959 and was introduced into therapy in 1962; it is still a first-line agent in the treatment of diseases such as tuberculosis, leprosy and various biofilm-related infections. The antimicrobial activity of RIF is due to its inhibition of bacterial RNA polymerase (RNAP). Most frequently, bacteria become resistant to RIF through mutation of the target; however, this mechanism is not unique.

A cell active chemical GEF inhibitor selectively targets the Trio/RhoG/Rac1 signaling pathway.

RhoGEFs (guanine nucleotide exchange factors of the Rho GTPase family) are upstream regulators of cell adhesion and migration pathways, thus representing attractive yet relatively unexplored targets for the development of anti-invasive drugs. We screened for chemical inhibitors of TrioN, the N-terminal GEF domain of the multidomain Trio protein, and identified ITX3 as a nontoxic inhibitor. In transfected mammalian cells, ITX3 blocked TrioN-mediated dorsal membrane ruffling and Rac1 activation while having no effect on GEF337-, Tiam1-, or Vav2-mediated RhoA or Rac1 activation.

Myxopyronin: a punch in the jaws of bacterial RNA polymerase.

Evaluation of: Belogurov GA, Vassylyeva MN, Sevostyanova A et al.: Transcription inactivation through local refolding of the RNA polymerase structure. Nature 457, 332-335 (2008) and, Mukhopadhyay J, Das K, Ismail S et al.

The antibiotics in the chemical space.

Ensuring the availability of new antibiotics to eradicate resistant pathogens is a critical issue, but very few new antibacterials have been recently commercialized. In an effort to rationalize their discovery process, the industry has utilized chemical library and high-throughput approaches already applied in other therapeutical areas to generate new antibiotics. This strategy has turned out to be poorly adapted to the reality of antibacterial discovery.

A novel druglike spleen tyrosine kinase binder prevents anaphylactic shock when administered orally.

Background: The spleen tyrosine kinase (Syk) is recognized as a potential pharmaceutical target for the treatment of type I hypersensitivity reactions including allergic rhinitis, urticaria, asthma, and anaphylaxis because of its critical position upstream of immunoreceptor signaling complexes that regulate inflammatory responses in leukocytes.

Objective: Our aim was to improve the selectivity of anti-Syk therapies by impeding the interaction of Syk with its cellular partners, instead of targeting its catalytic site.

Methods: We have previously studied the inhibitory effects of the anti-Syk intracellular antibody G4G11 on Fc epsilonRI-induced release of allergic mediators.

Structure-activity relationships of phenyl-furanyl-rhodanines as inhibitors of RNA polymerase with antibacterial activity on biofilms.

The dramatic rise of antibiotic-resistant bacteria over the past two decades has stressed the need for completely novel classes of antibacterial agents. Accordingly, recent advances in the study of prokaryotic transcription open new opportunities for such molecules. This paper reports the structure-activity relationships of a series of phenyl-furanyl-rhodanines (PFRs) as antibacterial inhibitors of RNA polymerase (RNAP).

Progress in targeting bacterial transcription.

The bacterial RNA polymerase (RNAP) is an essential enzyme that is responsible for making RNA from a DNA template and is targeted by several antibiotics. Rifampicin was the first of such antibiotics to be described and is one of the most efficient anti-tuberculosis drugs in use. In the past five years, structural studies of bacterial RNAP and the resolution of several complexes of drugs bound to RNAP subunits have revealed molecular details of the drug-binding sites and the mechanism of drug action.

In vitro activity of a new antibacterial rhodanine derivative against Staphylococcus epidermidis biofilms.

Objectives: Staphylococcus epidermidis biofilms form at the surface of implants and prostheses and are responsible for the failure of many antibiotic therapies. Only a few antibiotics are relatively active against biofilms, and rifampicin, a transcription inhibitor, is among the most effective molecules for treating biofilm-related infections. Having recently selected a new potential transcription inhibitor, we attempted to evaluate its efficacy against S.

Identification of TRIO-GEFD1 chemical inhibitors using the yeast exchange assay.

Background Information: Rho GTPases are involved in many biological processes and participate in cancer development. Their activation is catalysed by exchange factors [RhoGEFs (Rho GTPase guanine nucleotide-exchange factor)] of the Dbl family. RhoGEFs display proto-oncogenic features, thus appearing as candidate targets for anticancer drugs.

Novel synthetic molecules targeting the bacterial RNA polymerase assembly.

Objectives: Despite extensive functional screening of the bacterial RNA polymerase (RNAP) over the past years, very few novel inhibitors have been reported. We have, therefore, decided to screen with a radically different, non-enzymic, protein-protein interaction assay. Our target is the highly conserved RNAP-sigma interaction that is essential for transcription.

Precise characterization of the epitope recognized by a monoclonal antibody against Escherichia coli RNA polymerase.

We have recently isolated a monoclonal antibody directed against Escherichia coli RNA polymerase that does not inhibit transcription. This antibody is a useful tool to immobilize this enzyme for transcription assays or protein-protein interaction studies. The epitope of this monoclonal antibody was precisely located by a combination of protein deletion and synthetic peptide scanning.

A multiwell assay to isolate compounds inhibiting the assembly of the prokaryotic RNA polymerase.

We have developed a multiwell assay for the detection of modulators of prokaryotic transcription based on the quantification of protein-protein interaction. This assay consists of three steps: (a) the immobilization of the Escherichia coli protein sigma70 in the well, (b) the incubation of the immobilized protein with core RNA polymerase and a potential inhibitor, and (c) washing and quantification of the binding of core to sigma70 with a monoclonal antibody conjugated to horseradish peroxidase. We show that this assay is sensitive, reproducible, and robust, and is able to discriminate between control competitors with different affinities.

The bacteriophage T4 late-transcription coactivator gp33 binds the flap domain of Escherichia coli RNA polymerase.

Transcription of bacteriophage T4 late genes requires concomitant DNA replication. T4 late promoters, which consist of a single 8-bp -10 motif, are recognized by a holoenzyme containing Escherichia coli RNA polymerase core and the T4-encoded promoter specificity subunit, gp55. Initiation of transcription at these promoters by gp55-holoenzyme is inefficient, but is greatly activated by the DNA-loaded DNA polymerase sliding clamp, gp45, and the coactivator, gp33.

Data processing and exchange tools to facilitate chemical genetic screening processes.

Due to the development of chemical genomics, the screening of chemical libraries is used more and more by research laboratories to identify small molecule inhibitors or activators of cell functions. To facilitate the treatment and archiving of screening data, we developed a multiuser web application called Elisa Data Exchanger (EDE). The program is able to automatically identify which chemical compounds were tested.