Dataset Information

Characterization of the phytochelatin synthase of Schistosoma mansoni.

ABSTRACT: Treatment for schistosomiasis, which is responsible for more than 280,000 deaths annually, depends exclusively on the use of praziquantel. Millions of people are treated annually with praziquantel and drug resistant parasites are likely to evolve. In order to identify novel drug targets the Schistosoma mansoni sequence databases were queried for proteins involved in glutathione metabolism. One potential target identified was phytochelatin synthase (PCS). Phytochelatins are oligopeptides synthesized enzymatically from glutathione by PCS that sequester toxic heavy metals in many organisms. However, humans do not have a PCS gene and do not synthesize phytochelatins. In this study we have characterized the PCS of S. mansoni (SmPCS). The conserved catalytic triad of cysteine-histidine-aspartate found in PCS proteins and cysteine proteases is also found in SmPCS, as are several cysteine residues thought to be involved in heavy metal binding and enzyme activation. The SmPCS open reading frame is considerably extended at both the N- and C-termini compared to PCS from other organisms. Multiple PCS transcripts are produced from the single encoded gene by alternative splicing, resulting in both mitochondrial and cytoplasmic protein variants. Expression of SmPCS in yeast increased cadmium tolerance from less than 50 µM to more than 1,000 µM. We confirmed the function of SmPCS by identifying PCs in yeast cell extracts using HPLC-mass spectrometry. SmPCS was found to be expressed in all mammalian stages of worm development investigated. Increases in SmPCS expression were seen in ex vivo worms cultured in the presence of iron, copper, cadmium, or zinc. Collectively, these results indicate that SmPCS plays an important role in schistosome response to heavy metals and that PCS is a potential drug target for schistosomiasis treatment. This is the first characterization of a PCS from a parasitic organism.

SUBMITTER: Ray D

PROVIDER: S-EPMC3101182 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Characterization of the phytochelatin synthase of Schistosoma mansoni.

Ray Debalina D Williams David L DL

PLoS neglected tropical diseases 20110524 5

Treatment for schistosomiasis, which is responsible for more than 280,000 deaths annually, depends exclusively on the use of praziquantel. Millions of people are treated annually with praziquantel and drug resistant parasites are likely to evolve. In order to identify novel drug targets the Schistosoma mansoni sequence databases were queried for proteins involved in glutathione metabolism. One potential target identified was phytochelatin synthase (PCS). Phytochelatins are oligopeptides synthesi ...[more]

PMID: 21629724

Similar Datasets

Project description:BackgroundThe chemotherapy of schistosomiasis currently depends on the use of a single drug, praziquantel. In order to develop novel chemotherapeutic agents we are investigating enzymes involved in the epigenetic modification of chromatin. Sirtuins are NAD+ dependent lysine deacetylases that are involved in a wide variety of cellular processes including histone deacetylation, and have been demonstrated to be therapeutic targets in various pathologies, including cancer.Methodology principal findingsIn order to determine whether Schistosoma mansoni sirtuins are potential therapeutic targets we first identified and characterized their protein sequences. Five sirtuins (SmSirt) are encoded in the S. mansoni genome and phylogenetic analysis showed that they are orthologues of mammalian Sirt1, Sirt2, Sirt5, Sirt6 and Sirt7. Both SmSirt1 and SmSirt7 have large insertion in the catalytic domain compared to their mammalian orthologues. SmSirt5 is the only mitochondrial sirtuin encoded in the parasite genome (orthologues of Sirt3 and Sirt4 are absent) and transcripts corresponding to at least five splicing isoforms were identified. All five sirtuins are expressed throughout the parasite life-cycle, but with distinct patterns of expression. Sirtuin inhibitors were used to treat both schistosomula and adult worms maintained in culture. Three inhibitors in particular, Sirtinol, Salermide and MS3 induced apoptosis and death of schistosomula, the separation of adult worm pairs, and a reduction in egg laying. Moreover, Salermide treatment led to a marked disruption of the morphology of ovaries and testes. Transcriptional knockdown of SmSirt1 by RNA interference in adult worms led to morphological changes in the ovaries characterized by a marked increase in mature oocytes, reiterating the effects of sirtuin inhibitors and suggesting that SmSirt1 is their principal target.Conclusion significanceOur data demonstrate the potential of schistosome sirtuins as therapeutic targets and validate screening for selective sirtuin inhibitors as a strategy for developing new drugs against schistosomiasis.

Dataset Information

Characterization of the phytochelatin synthase of Schistosoma mansoni.

Publications

Characterization of the phytochelatin synthase of Schistosoma mansoni.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets