The effects of Brazilian and Bulgarian propolis in vitro against Salmonella Typhi and their synergism with antibiotics acting on the ribosome

Salmonella enterica serovar Typhi is the causative agent of typhoid fever in humans, and the use of antibiotics is essential for controlling this infection; however, the excessive use of antibiotics may select resistant strains. Propolis is a honeybee product and its antimicrobial activity has been intensively investigated. Thus, the objective of this study was to investigate a possible synergism between propolis (collected in Brazil and Bulgaria) and antibiotics acting on the ribosome (chloramphenicol, tetracycline and neomycin) against Salmonella Typhi in vitro. The synergism was investigated by using 1/2 and 1/4 of the minimum inhibitory concentration for propolis and these antimicrobial agents, evaluating the number of viable cells according to the incubation time. Brazilian propolis showed a bacteriostatic action against S. Typhi, while Bulgarian propolis showed a bactericidal activity and a synergistic effect with the three antibiotics. Variations in the biological assays might be due to the differences in their chemical compositions. Based on the results, one may conclude that Bulgarian propolis showed an important antibacterial action, as well as a synergistic effect with antibiotics acting on the ribosome, which points out a possible therapeutic strategy evaluating the use of propolis preparations for the treatment of Salmonella Typhi infection.

Hypusine Modification of the Ribosome-binding Protein eIF5A, a Target for New Anti-Inflammatory Drugs: Understanding the Action of the Inhibitor GC7 on a Murine Macrophage Cell Line

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Capturing Transition Paths and Transition States for Conformational Rearrangements in the Ribosome

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo das interações de eIF5A com a maquinaria de tradução e com o complexo Ribosome Quality Control, utilizando modelo de Saccharomyces cerevisiae

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Immunological response in mice bearing LM3 breast tumor undergoing Pulchellin treatment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Synthetic lethality between eIF5A and Ypt1 reveals a connection between translation and the secretory pathway in yeast

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Production of active recombinant eIF5A: reconstitution in E.coli of eukaryotic hypusine modification of eIF5A by its coexpression with modifying enzymes

Eukaryotic translation initiation factor 5A (eIF5A) is the only cellular protein that contains the polyamine-modified lysine, hypusine [N(epsilon)-(4-amino-2-hydroxybutyl)lysine]. Hypusine occurs only in eukaryotes and certain archaea, but not in eubacteria. It is formed post-translationally by two consecutive enzymatic reactions catalyzed by deoxyhypusine synthase (DHS) and deoxyhypusine hydroxylase (DOHH). Hypusine modification is essential for the activity of eIF5A and for eukaryotic cell proliferation. eIF5A binds to the ribosome and stimulates translation in a hypusine-dependent manner, but its mode of action in translation is not well understood. Since quantities of highly pure hypusine-modified eIF5A is desired for structural studies as well as for determination of its binding sites on the ribosome, we have used a polycistronic vector, pST39, to express eIF5A alone, or to co-express human eIF5A-1 with DHS or with both DHS and DOHH in Escherichia coli cells, to engineer recombinant proteins, unmodified eIF5A, deoxyhypusine- or hypusine-modified eIF5A. We have accomplished production of three different forms of recombinant eIF5A in high quantity and purity. The recombinant hypusine-modified eIF5A was as active in methionyl-puromycin synthesis as the native, eIF5A (hypusine form) purified from mammalian tissue. The recombinant eIF5A proteins will be useful tools in future structure/function and the mechanism studies in translation.

eIF5A has a function in the elongation step of translation in yeast

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

eIF5A interacts functionally with eEF2

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Molecular characterization of Blastocrithidia culicis L17 ribosomal protein

Blastocrithidia culicis is a protozoan of the family Trypanosomatidae. It is a parasite of insects, but the presence of bacteriumlike endosymbionts in its cytoplasm led some investigators to study this protozoan. This trypanosomatid does not infect humans and although it is phylogenetically distant from Trypanosoma cruzi, it presents many morphological characteristics, which are similar. In previous studies our group showed the presence of a L27 ribosomal protein in T cruzi (named TcrL27) using a RT-PCR, which also resulted in the cloning, sequencing and expression of an unexpected ribosomal protein, L17, in Blastocrithidia culicis (BcL17). In this paper, Western blot analysis demonstrated that the anti-BcL17 antibody recognizes the presence of the same ribosomal protein either in Blastochritidia culicis and T. cruzi nuclear extracts. Besides, two similar bands (40 and 47 kDa) appeared also in T. cruzi isolated ribosomal proteins and B. culicis nuclear extract corroborating with the findings showed in the phylogenetic reconstruction. With respect to their localization within the ribosome, both the L17 and L27 ribosomal proteins appear to belong to the peptidyl-transferase site, and are therefore part of the key step in protein synthesis. Both ribosomal proteins bind spiramycin derivatives, being therefore compounds of the macrolides connection sites in the ribosome. These findings would open a possibility to better evaluate this issue.

Is there a role for eIF5A in translation?

The putative translation factor eIF5A is essential for cell viability and is highly conserved from archaebacteria to mammals. This factor is the only cellular protein that undergoes an essential posttranslational modification dependent on the polyamine spermidine, called hypusination. This review focuses on the functional characterization of eIF5A. Although this protein was originally identified as a translation initiation factor, subsequent studies did not support a role for eIF5A in general translation initiation. eIF5A has also been implicated in nuclear export of HIV-1 Rev and mRNA decay, but these findings are controversial in the literature and may reflect secondary effects of eIF-5A function. Next, the involvement of eIF5A and hypusination in the control of the cell cycle and proliferation in various organisms is reviewed. Finally, recent evidence in favor of reconsidering the role of eIF5A as a translation factor is discussed. Future studies may reveal the specific mechanism by which eIF5A affects protein synthesis.

eIF5A binds to translational machinery components and affects translation in yeast

The putative translation factor eIF5A is essential for cell viability and is highly conserved from archebacteria to mammals. Although this protein was originally identified as a translation initiation factor, subsequent experiments did not support a role for eIF5A in general translation. In this work, we demonstrate that eIF-5A interacts with structural components of the 80S ribosome, as well as with the translation elongation factor 2 (eEF2). Moreover, eIF5A is further shown to cofractionate with monosomes in a translation-dependent manner. Finally, eIF5A mutants show altered polysome profiles and are sensitive to translation inhibitors. Our results re-establish a function for eIF5A in translation and suggest a role for this factor in translation elongation instead of translation initiation. (c) 2006 Elsevier B.V. All rights reserved.

Antibacterial effects of Brazilian and Bulgarian propolis and synergistic effects with antibiotics acting on the bacterial DNA and folic acid

Propolis is a honeybee product that has been used since ancient times because of its therapeutic effects. It can be used in the development of alternative therapies for the treatment of many diseases, and because propolis shows antibacterial action, this work was carried out in order to investigate a possible synergism between propolis and antibiotics acting on DNA (ciprofloxacin and norfloxacin) and on the metabolism (cotrimoxazole) against Salmonella Typhi. Propolis samples collected in Brazil and Bulgaria were compared in these assays, and the synergism was investigated by using 1/2 and 1/4 of the minimal inhibitory concentration for propolis and antibiotics, evaluating the number of viable cells according to the incubation time. Brazilian and Bulgarian propolis showed antibacterial activity, but no synergistic effects with the three tested antibiotics were seen. Previous works by our laboratory have revealed that propolis has synergistic effects with antibiotics, acting on the bacterial wall and ribosome, but it does not seem to interact with antibiotics acting on DNA or folic acid, and only a bacteriostatic action was seen in these assay conditions.

The 5S rDNA family evolves through concerted and birth-and-death evolution in fish genomes: an example from freshwater stingrays

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)