Modified peptides and organic metabolites of cyanobacterial origin with antiplasmodial properties

As etiological agents of malaria disease, Plasmodium spp. parasites are responsible for one of the most severe global health problems occurring in tropical regions of the world. This work involved compiling marine cyanobacteria metabolites reported in the scientific literature that exhibit antiplasmodial activity. Out of the 111 compounds mined and 106 tested, two showed antiplasmodial activity at very low concentrations, with IC50 at 0.1 and 1.5 nM (peptides: dolastatin 10 and lyngbyabellin A, 1.9% of total tested). Examples of chemical derivatives generated from natural cyanobacterial compounds to enhance antiplasmodial activity and Plasmodium selectivity can be found in successful findings from nostocarboline, eudistomin, and carmaphycin derivatives, while bastimolide derivatives have not yet been found. Overall, 57% of the reviewed compounds are peptides with modified residues producing interesting active moieties, such as α- and β-epoxyketone in camaphycins. The remaining compounds belong to diverse chemical groups such as alkaloids, macrolides, polycyclic compounds, and halogenated compounds. The Dolastatin 10 and lyngbyabellin A, compounds with antiplasmodial high activity, are cytoskeletal disruptors with different protein targets.

Development of Anxiolytic and Depression-like Behavior in Mice Infected with Mycobacterium lepraemurium

Murine leprosy is a systemic infectious disease of mice caused by Mycobacterium lepraemurium (MLM) in which the central nervous system (CNS) is not infected; nevertheless, diseased animals show measurable cognitive alterations. For this reason, in this study, we explored the neurobehavioral changes in mice chronically infected with MLM. BALB/c mice were infected with MLM, and 120 days later, the alterations in mice were evaluated based on immunologic, histologic, endocrine, neurochemical, and behavioral traits. We found increases in the levels of IL-4 and IL-10 associated with high bacillary loads. We also found increase in the serum levels of corticosterone, epinephrine, and norepinephrine in the adrenal gland, suggesting neuroendocrine deregulation. Mice exhibited depression-like behavior in the tail suspension and forced swimming tests and anxiolytic behavior in the open field and elevated plus maze tests. The neurobehavioral alterations of mice were correlated with the histologic damage in the prefrontal cortex, ventral hippocampus, and amygdala, as well as with a blood-brain barrier disruption in the hippocampus. These results reveal an interrelated response of the neuroimmune-endocrinological axis in unresolved chronic infections that result in neurocognitive deterioration.

In silico analysis of putative metal response elements (MREs) in the zinc-responsive genes from Trichomonas vaginalis and the identification of novel palindromic MRE-like motif

Zinc is an essential micronutrient that plays an important role as a co-factor to several proteins, including zinc-responsive transcription factors. Trichomonas vaginalis is able to survive in the presence of high zinc concentrations in the male urogenital tract. Several genes in T. vaginalis have been shown to respond to changes in zinc concentrations, however, the zinc-dependent mechanism remains undetermined. Recently, we identified in T. vaginalis the zinc finger protein, TvZNF1, which is an ortholog of the mammal metal transcription factor (MTF1). We searched for several of the zinc-responsive genes in T. vaginalis to determine whether if they contain metal response elements (MRE), cis-acting DNA elements that specifically bind MTF1. Six highly conserved over-represented sequence motifs (TvMREs), which share similarity with other eukaryotic MREs, were identified in the zinc-responsive genes in T. vaginalis. We also demonstrated that some of the TvMREs assemble as divalent complexes either as two closely spaced TvMREs or as two overlapping TvMREs forming a palindromic-like sequence: TGCC(N3)GGCA. Electrophoretic mobility shift assays were used to detect the zinc-dependent binding of TvZNF1 and nuclear proteins from T. vaginalis to this specific palindromic motif. Our results support a novel mechanism used by T. vaginalis for the transcriptional regulation of associated zinc-responsive genes through a MTF1/MRE-like system.

Genome-wide identification, in silico characterization and expression analysis of ZIP-like genes from Trichomonas vaginalis in response to Zinc and Iron

Trace elements such as Zinc and Iron are essential components of metalloproteins and serve as cofactors or structural elements for enzymes involved in several important biological processes in almost all organisms. Because either excess or insufficient levels of Zn and Fe can be harmful for the cells, the homeostatic levels of these trace minerals must be tightly regulated. The Zinc regulated transporter, Iron regulated transporter-like Proteins (ZIP) comprise a diverse family, with several paralogues in diverse organisms and are considered essential for the Zn and Fe uptake and homeostasis. Zn and Fe has been shown to regulate expression of proteins involved in metabolism and pathogenicity mechanisms in the protozoan pathogen Trichomonas vaginalis, in contrast high concentrations of these elements were also found to be toxic for T. vaginalis trophozoites. Nevertheless, Zn and Fe uptake and homeostasis mechanisms is not yet clear in this parasite. We performed a genome-wide analysis and localized the 8 members of the ZIP gene family in T. vaginalis (TvZIP1-8). The bioinformatic programs predicted that the TvZIP proteins are highly conserved and show similar properties to the reported in other ZIP orthologues. The expression patterns of TvZIP1, 3, 5 and 7 were diminished in presence of Zinc, while the rest of the TvZIP genes showed an unchanged profile in this condition. In addition, TvZIP2 and TvZIP4 showed a differential expression pattern in trophozoites growth under different Iron conditions. These results suggest that TvZIP genes encode membrane transporters that may be responsible for the Zn and Fe acquisition in T. vaginalis.

Translation initiation factor eIF-5A, the hypusine-containing protein, is phosphorylated on serine and tyrosine and O-glycosylated in Trichomonas vaginalis

The eukaryotic translation factor eIF-5A is highly conserved throughout eukaryotes and undergoes an unusual polyamine-dependent post-translational modification called hypusination. Trichomonas vaginalis has two tveif-5a genes (tveif-5a1 and tveif-5a2), each encoding a 19-kDa protein. In this report, we describe the detection of two forms with different isoelectric points (5.2 and 5.5) that correspond to the precursor and mature TveIF-5A, respectively. In addition, we demonstrated that only the mature form of TveIF-5A is phosphorylated and glycosylated via two-dimensional gel electrophoresis-western blot (2DE-WB) assays using anti-phosphoserine and anti-phosphotyrosine antibodies and the SNA, ConA and MAA lectins. Interestingly, when the protozoa were grown in 1,4-diamino-2-butanone (DAB), an inhibitor of putrescine biosynthesis, and transferred to medium containing exogenous putrescine, a new spot with an isoelectric point of 5.3 was observed, presumably corresponding to a phosphorylated intermediate or deoxyhypusine form. Our data indicate that, in T. vaginalis, phosphorylations and glycosylations are necessary to obtain the mature TveIF-5A, and we confirm the identity of the precursor, intermediate and mature forms of TveIF-5A by mass spectrometry analysis.

Identification of two novel Trichomonas vaginalis eif-5a genes

The eukaryotic translation initiation factor 5A (eIF-5A) is highly conserved and is the only protein that is known to contain the unique and essential amino acid residue hypusine. Synthesis of hypusine is essential for the function of eIF5A in eukaryotic cell proliferation and survival. In this study, we identified two novel eukaryotic translation initiation factor 5A (eIF-5A) genes in Trichomonas vaginalis. The tveif-5a1 and tveif-5a2 putative genes were localized in different contigs, both containing ORFs encoding proteins of 168 amino acids that share high sequence identity with eIF-5A sequences from other eukaryotic organisms. A phylogenetic tree constructed with TveIF-5A1 and TveIF-5A2 from T. vaginalis and 13 other eIF-5A sequences of eukaryotic and archaebacterial origin revealed that both trichomonal TveIF-5As show the highest degree of similarity to bacteria. Using an anti-TveIF-5A antibody, we detected two protein bands and spots of 19 and 20kDa with isoelectric points (pI) of 5.2 and 5.5, respectively, by one and two-dimensional Western blot assays. In addition, we used reverse transcription polymerase chain reaction (RT-PCR) to demonstrate that both of these tveif-5a genes are expressed in T. vaginalis. Immunofluorescence assays showed that the TveIF-5A protein was dispersed throughout the parasite cytoplasm. In conclusion, T. vaginalis has two eif-5a genes, and both genes are expressed as highly conserved proteins of 19kDa, which are localized in the cytoplasm of this parasite.

A novel cysteine proteinase (CP65) of Trichomonas vaginalis involved in cytotoxicity

The goal of this study was to demonstrate the participation in cellular damage of a Trichomonas vaginalis proteinase with a molecular mass of 65 kDa (CP65). By two dimensional gelatin-gel electrophoresis of trichomonad proteins we detected four spots with proteolytic activity on the 65 kDa region, but only one, pI 7.2, binds to the HeLa cell surface. By indirect immunofluorescence, rabbit antibodies against this proteinase localized the CP65 on the plasma membrane and in the cytoplasm of T. vaginalis. Pretreatment of parasites with the specific anti-CP65 antibody reduced trichomonal cytotoxicity to HeLa cell monolayers. The specific cysteine proteinase inhibitor, L-3-carboxy-2, 3-trans-epoxypropionyl-leucylamido (4-guanidino) butane (E64) abrogated the proteinase activity and reduced cytotoxicity levels of T. vaginalis in cell culture monolayers, indicating that the trichomonad CP65 is a cysteine proteinase. Activity of the CP65 proteinase was optimal at pH 5.5 and 37 degrees C, conditions similar to those of patients with trichomonosis. Also, this proteinase degraded some of the proteins found in the vagina, i.e. collagen IV and fibronectin, but not laminin-1 or haemoglobin. Finally, immunoprecipitation assays showed that sera and vaginal washes from trichomonosis patient possess anti-CP65 antibodies. In conclusion, results presented in this work demonstrate that the CP65 is a surface cysteine proteinase involved in T. vaginalis cytotoxicity to HeLa cell monolayers, as a virulence factor. It is immunogenic during human infection and degrades some extracellular matrix proteins, i.e. collagen IV and fibronectin.