Screening for small molecule modulators of Trypanosoma brucei Hsp70 chaperone activity based upon alcyonarian coral-derived natural products
- Authors: Andreassend, Sarah K , Bentley, Stephen , Blatch, Gregory L , Boshoff, Aileen , Keyzers, Robert A
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426045 , vital:72309 , xlink:href="https://doi.org/10.3390/md18020081"
- Description: The Trypanosoma brucei Hsp70/J-protein machinery plays an essential role in survival, differentiation, and pathogenesis of the protozoan parasite, and is an emerging target against African Trypanosomiasis. This study evaluated a set of small molecules, inspired by the malonganenones and nuttingins, as modulators of the chaperone activity of the cytosolic heat inducible T. brucei Hsp70 and constitutive TbHsp70.4 proteins. The compounds were assessed for cytotoxicity on both the bloodstream form of T. b. brucei parasites and a mammalian cell line. The compounds were then investigated for their modulatory effect on the aggregation suppression and ATPase activities of the TbHsp70 proteins. A structure–activity relationship for the malonganenone-class of alkaloids is proposed based upon these results.
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- Date Issued: 2020
Challenges and curriculum transformation in the higher education sector in South Africa: a case study in WASH to improve the training of pharmacists
- Authors: Tandlich, Roman , Ngqwala, Nosiphiwe P , Boshoff, Aileen , Madikizela, Phindile , Srinivas, Sunitha C , Pyle, Desmond M , Oosthuizen, Rene
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76858 , vital:30631 , https://doi.org/10.2478/atd-2018-0001
- Description: South Africa is a member state of the “BRICS” bloc (BRICS2017.org, 2017) and the G20 group of the 20 nations/economic blocs, which between them account for the majority of the world’s trade and economic activity. It faces many developmental challenges which are mirrored in its higher education sector. In this article, the authors seek to provide an overview of the challenges that South African higher education faces in the achievement of the developmental goals of the country. The focus of this paper is a case study in WASH (water, sanitation and hygiene) to improve context-specific responses that trains pharmacists on knowledge and skills.
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- Date Issued: 2018
Plasmodium falciparum Hep1 is required to prevent the self aggregation of PfHsp70-3
- Authors: Nyakundi, David O , Vuko, Loyiso A M , Bentley, Stephen J , Hoppe, Heinrich C , Blatch, Gregory L , Boshoff, Aileen
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66109 , vital:28903 , https://doi.org/10.1371/journal.pone.0156446
- Description: publisher version , The majority of mitochondrial proteins are encoded in the nucleus and need to be imported from the cytosol into the mitochondria, and molecular chaperones play a key role in the efficient translocation and proper folding of these proteins in the matrix. One such molecular chaperone is the eukaryotic mitochondrial heat shock protein 70 (Hsp70); however, it is prone to self-aggregation and requires the presence of an essential zinc-finger protein, Hsp70-escort protein 1 (Hep1), to maintain its structure and function. PfHsp70-3, the only Hsp70 predicted to localize in the mitochondria of P. falciparum, may also rely on a Hep1 orthologue to prevent self-aggregation. In this study, we identified a putative Hep1 orthologue in P. falciparum and co-expression of PfHsp70-3 and PfHep1 enhanced the solubility of PfHsp70-3. PfHep1 suppressed the thermally induced aggregation of PfHsp70-3 but not the aggregation of malate dehydrogenase or citrate synthase, thus showing specificity for PfHsp70-3. Zinc ions were indeed essential for maintaining the function of PfHep1, as EDTA chelation abrogated its abilities to suppress the aggregation of PfHsp70-3. Soluble and functional PfHsp70-3, acquired by co-expression with PfHep-1, will facilitate the biochemical characterisation of this particular Hsp70 protein and its evaluation as a drug target for the treatment of malaria. , This work was funded by grants from the National Research Foundation (NRF); grant number 87663 and Deutsche Forschungsgemeinschaft (DFG); grant number LI 402/14-1. D.O.N. is the recipient of academic development and training funds from Mwenge Catholic University, Moshi, Tanzania. S.J.B. is the recipient of an NRF Doctoral Innovation Scholarship.
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- Date Issued: 2016
The Malarial Exported PFA0660w Is an Hsp40 Co-Chaperone of PfHsp70-x
- Authors: Daniyan, Michael O , Boshoff, Aileen , Prinsloo, Earl , Pesce, Eva-Rachele , Blatch, Gregory L
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66098 , vital:28901 , https://doi.org/10.1371/journal.pone.0148517
- Description: publisher version , Plasmodium falciparum, the human pathogen responsible for the most dangerous malaria infection, survives and develops in mature erythrocytes through the export of proteins needed for remodelling of the host cell. Molecular chaperones of the heat shock protein (Hsp) family are prominent members of the exportome, including a number of Hsp40s and a Hsp70. PFA0660w, a type II Hsp40, has been shown to be exported and possibly form a complex with PfHsp70-x in the infected erythrocyte cytosol. However, the chaperone properties of PFA0660w and its interaction with human and parasite Hsp70s are yet to be investigated. Recombinant PFA0660w was found to exist as a monomer in solution, and was able to significantly stimulate the ATPase activity of PfHsp70-x but not that of a second plasmodial Hsp70 (PfHsp70-1) or a human Hsp70 (HSPA1A), indicating a potential specific functional partnership with PfHsp70-x. Protein binding studies in the presence and absence of ATP suggested that the interaction of PFA0660w with PfHsp70-x most likely represented a co-chaperone/chaperone interaction. Also, PFA0660w alone produced a concentration-dependent suppression of rhodanese aggregation, demonstrating its chaperone properties. Overall, we have provided the first biochemical evidence for the possible role of PFA0660w as a chaperone and as co-chaperone of PfHsp70-x. We propose that these chaperones boost the chaperone power of the infected erythrocyte, enabling successful protein trafficking and folding, and thereby making a fundamental contribution to the pathology of malaria. , This work was supported by grants from the National Research Foundation (NRF) and Medical Research Council (MRC) of South Africa. The ProteOn XPR36 IAS was purchased from a National Nanotechnology Equipment Programme grant from the Department of Science and Technology and the NRF of South Africa. Michael O. Daniyan was a recipient of the Education Trust Fund (ETF) Academic Staff Training and Development (AST and D) scholarship of Obafemi Awolowo University, Ile-Ife, Nigeria and a Rhodes University Council research bursary
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- Date Issued: 2016
PFB0595w is a Plasmodium falciparum J protein that co-localizes with PfHsp70-1 and can stimulate its in vitro ATP hydrolysis activity
- Authors: Njunge, James M , Mandal, Pradipta , Przyborski, Jude M , Boshoff, Aileen , Pesce, Eva-Rachele , Blatch, Gregory L
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431739 , vital:72800 , xlink:href="https://doi.org/10.1016/j.biocel.2015.02.008"
- Description: Heat shock proteins, many of which function as molecular chaperones, play important roles in the lifecycle and pathogenesis of the malaria parasite, Plasmodium falciparum. The P. falciparum heat shock protein 70 (PfHsp70) family of chaperones is potentially regulated by a large complement of J proteins that localize to various intracellular compartments including the infected erythrocyte cytosol. While PfHsp70-1 has been shown to be an abundant cytosolic chaperone, its regulation by J proteins is poorly understood. In this study, we characterized the J protein PFB0595w, a homologue of the well-studied yeast cytosolic J protein, Sis1. PFB0595w, similarly to PfHsp70-1, was localized to the parasite cytosol and its expression was upregulated by heat shock. Additionally, recombinant PFB0595w was shown to be dimeric and to stimulate the in vitro ATPase activity of PfHsp70-1. Overall, the expression, localization and biochemical data for PFB0595w suggest that it may function as a cochaperone of PfHsp70-1, and advances current knowledge on the chaperone machinery of the parasite.
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- Date Issued: 2015
Trypanosoma brucei J protein 2 is a stress inducible and essential Hsp40
- Authors: Ludewig, Michael H , Boshoff, Aileen , Horn, David , Blatch, Gregory L
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431798 , vital:72804 , xlink:href="https://doi.org/10.1016/j.biocel.2014.12.016"
- Description: Hsp40 proteins (also known as DnaJ or J proteins) serve as co-chaperones for Hsp70, but also display evidence of independent chaperone function. Furthermore, certain Hsp40s have been shown to be stress-inducible and essential. Trypanosomatids display a remarkable diversification of Hsp40 proteins, with numerous distinct Hsp40-like proteins encoded in the Trypanosoma brucei genome. This study investigated the role of one of the six T. brucei Type I Hsp40s, T. brucei J protein 2 (Tbj2). We found that Tbj2 was heat stress-inducible, and that knockdown using RNA interference resulted in a severe growth defect under normal growth temperatures. Furthermore, a green fluorescent protein (GFP)-Tbj2 fusion protein was found to be localized to the cytosol of T. brucei. Taken together, these data suggest that Tbj2 is not functionally equivalent to the other five Type I Hsp40s, and that it is an essential, cytosolic, and stress-inducible chaperone, potentially playing an important role in protein biogenesis in T. brucei.
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- Date Issued: 2015
Investigating the chaperone properties of a novel heat shock protein, Hsp70. c, from Trypanosoma brucei
- Authors: Burger, Adélle , Ludewig, Michael H , Boshoff, Aileen
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431155 , vital:72749 , xlink:href="https://doi.org/10.1155/2014/172582"
- Description: The neglected tropical disease, African Trypanosomiasis, is fatal and has a crippling impact on economic development. Heat shock protein 70 (Hsp70) is an important molecular chaperone that is expressed in response to stress and Hsp40 acts as its co-chaperone. These proteins play a wide range of roles in the cell and they are required to assist the parasite as it moves from a cold blooded insect vector to a warm blooded mammalian host. A novel cytosolic Hsp70, from Trypanosoma brucei, TbHsp70.c, contains an acidic substrate binding domain and lacks the C-terminal EEVD motif.The ability of a cytosolic Hsp40 from Trypanosoma brucei J protein 2, Tbj2, to function as a co-chaperone of TbHsp70.c was investigated.The main objective was to functionally characterize TbHsp70.c to further expand our knowledge of parasite biology. TbHsp70.c and Tbj2 were heterologously expressed and purified and both proteins displayed the ability to suppress aggregation of thermolabile MDH and chemically denatured rhodanese. ATPase assays revealed a 2.8-fold stimulation of the ATPase activity of TbHsp70.c by Tbj2. TbHsp70.c and Tbj2 both demonstrated chaperone activity and Tbj2 functions as a co-chaperone of TbHsp70.c.In vivo heat stress experiments indicated upregulation of the expression levels of TbHsp70.c.
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- Date Issued: 2014
Selective modulation of plasmodial Hsp70s by small molecules with antimalarial activity
- Authors: Cockburn, Ingrid , Boshoff, Aileen , Pesce, Eva-Rachele , Blatch, Gregory L
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431192 , vital:72752 , xlink:href="https://doi.org/10.1515/hsz-2014-0138"
- Description: Plasmodial heat shock protein 70 (Hsp70) chaperones represent a promising new class of antimalarial drug targets because of the important roles they play in the survival and pathogenesis of the malaria parasite Plasmodium falciparum. This study assessed a set of small molecules (lapachol, bromo-β-lapachona and malonganenones A, B and C) as potential modulators of two biologically important plasmodial Hsp70s, the parasite-resident PfHsp70-1 and the exported PfHsp70-x. Compounds of interest were assessed for modulatory effects on the steady-state basal and heat shock protein 40 (Hsp40)-stimulated ATPase activities of PfHsp70-1, PfHsp70-x and human Hsp70, as well as on the protein aggregation suppression activity of PfHsp70-x. The antimalarial marine alkaloid malonganenone A was of particular interest, as it was found to have limited cytotoxicity to mammalian cell lines and exhibited the desired properties of an effective plasmodial Hsp70 modulator. This compound was found to inhibit plasmodial and not human Hsp70 ATPase activity (Hsp40-stimulated), and hindered the aggregation suppression activity of PfHsp70-x. Furthermore, malonganenone A was shown to disrupt the interaction between PfHsp70-x and Hsp40. This is the first report to show that PfHsp70-x has chaperone activity, is stimulated by Hsp40 and can be specifically modulated by small molecule compounds.
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- Date Issued: 2014
Localisation of Theiler's murine encephalomyelitis virus protein 2C to the golgi apparatus using antibodies generated against a peptide region:
- Authors: Jauka, Tembisa , Mutsvunguma, Lorraine Z , Boshoff, Aileen , Edkins, Adrienne L , Knox, Caroline M
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165074 , vital:41206 , DOI: 10.1016/j.jviromet.2010.05.009
- Description: The picornavirus 2C protein is highly conserved and indispensible for virus replication. Polyclonal antibodies against Theiler's murine encephalomyelitis virus (TMEV) 2C protein were generated by immunisation of rabbits with a peptide comprising amino acids 31–210 of the protein. Antibodies were used to investigate the localisation of 2C in infected cells by indirect immunofluorescence and confocal microscopy. Analysis of infected cells revealed that the distribution of 2C changed during infection.
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- Date Issued: 2010