Characterisation of the plasmodium falciparum Hsp40 chaperones and their partnerships with Hsp70

Central to this research, 40 kDa Heat shock proteins (Hsp40s) are known to partner (or cochaperone) 70 kDa Heat shock proteins (Hsp70s), facilitating the selection and transfer of protein substrate to Hsp70 and the stimulation of the protein folding ability of Hsp70. Members of the diverse Hsp70-Hsp40 protein complement of Plasmodium falciparum have been implicated in the cytoprotection of this malaria parasite, and are thought to facilitate the protein folding, assembly and translocation tasks required by the parasite to commandeer the infected human erythrocyte subsequent to invasion. In particular, the parasite has evolved an expanded and specialised 43- member suite of Hsp40 proteins, 19 of which bear an identifiable export motif for secretion into the infected erythrocyte cytoplasm where they potentially interact with human Hsp70. Although type I Hsp40 proteins are representative of typical regulators of Hsp70 activity, only two of these proteins are apparent in the parasite’s Hsp40 complement. These include a characteristic type I Hsp40 termed PfHsp40, and a larger, atypical type I Hsp40 termed Pfj1. Both Hsp40 proteins are predicted to be parasite-resident and are most likely to facilitate the co-chaperone regulation of the highly abundant and stress-inducible Hsp70 homolog, PfHsp70-I. In this work, the co-chaperone functionality of PfHsp40 and Pfj1 was elucidated using in vivo and in vitro assays. Purified recombinant PfHsp40 was shown to stimulate the ATPase activity of PfHsp70-I in in vitro single turnover and steady state ATPase assays, and co-operate with PfHsp70-I in in vitro aggregation suppression assays. In these in vitro assays, heterologous partnerships could be demonstrated between PfHsp70-I and the human Hsp40, Hsj1a, and human Hsp70 and PfHsp40, suggesting a common mode of Hsp70-Hsp40 interaction in the parasite and host organism. The functionality of the signature Hsp40 domain, the Jdomain, of Pfj1 was demonstrated by its ability to replace the equivalent domain of the A. tumefaciens Hsp40, Agt DnaJ, in interactions with the prokaryotic Hsp70, DnaK, in the thermosensitive dnaJ cbpA E. coli OD259 deletion strain. An H33Q mutation introduced into the invariant and crucial HPD tripeptide motif abrogated the functionality of the J-domain in the in vivo complementation system. These findings provide the first evidence for the conservation of the prototypical mode of J-domain based interaction of Hsp40 with Hsp70 in P. falciparum. Immunofluorescence staining revealed the localisation of PfHsp40 to the parasite cytoplasm, and Pfj1 to the parasite cytoplasm and nucleus in cultured intraerythrocytic stage P. falciparum parasites. PfHsp70-I was also shown to localise to the parasite cytoplasm and nucleus in these stages, consistent with the literature. Overall we propose that PfHsp40 and Pfj1 co-localise with and regulate the chaperone activity of PfHsp70-I in P. falciparum. This is the first study to identify and provide evidence for a functional Hsp70-Hsp40 partnership in P. falciparum, and provides a platform for future studies to elucidate the importance of these chaperone partnerships in the establishment and survival of the parasite in the intraerythrocytic-stages of development

A framework to drive business growth in developing countries using omni-channel strategies

During the past few decades, firms have undergone radical changes due to digitalisation initiatives, changing consumer behaviour and other factors, such as the pandemic. This has led to, amongst others, the implementation of online strategies such as an omni-channel strategy. However, omni-channel strategies increase supply chain complexities and have very specific managerial implications to consider. Current research addresses numerous benefits of and barriers to online strategies and provides building blocks to implement online strategies. From this, a theoretical foundation was built for this article. Interviews were conducted in a developing country to determine the extent to which the theoretical foundation can be applied within the context of a developing country. This general qualitative research proposes a framework for managers in developing countries to consider when implementing an omni-channel strategy.https://www.inderscienceonline.com/journal/ijbpm2024-05-22hj2024Business ManagementSDG-09: Industry, innovation and infrastructur

Becoming a teacher

This book disseminates original research on learning in and from practice in pre-service teacher education. Authors such as Lederman and Lederman describe the student teaching practicum (or work-integrated learning [WIL]), which is an essential component of pre-service teacher education, as the ‘elephant in the room’. These authors note that 'the capstone experience in any teacher education programme is the student teaching practicum… [a]fter all, this is where the rubber hits the road'. However, many teacher educators will agree that this WIL component is sometimes very insufficient in assisting the student teacher to develop their own footing and voice as a teacher. This is the ‘gap’ that this research book addresses. Most of the chapters in the book report empirical data, with the exception of two chapters that can be categorized as systematic reviews. WIL is addressed from various angles in the chapters. Chapter 6 focuses on research related to what makes Finnish teacher education so effective, and in Chapter 4 researchers of the University of Johannesburg disseminate their findings on establishing a teaching school (based on Finnish insights) in Johannesburg. Chapter 3 highlights the challenges faced in open-and distance learning teacher education contexts. Several of the chapters disseminate research findings on alternative interventions to classic WIL, namely, where “safe spaces” or laboratories are created for student teachers to learn and grow professionally. These could either be simulations, such as software programmes and avatars in the intervention described in Chapter 2; student excursions, as the findings in chapters 5, 7 and 10 portray; or alternative approaches to WIL (e.g. Chapters 11 and 12). The book is devoted to scholarship in the field of pre-service teacher education. The target audience is scholars working in the fields of pre-service teacher education, work-integrated learning, and self-directed learning. The book makes a unique contribution in terms of firstly its extensive use of Cultural-Historical Activity Theory as a research lens, and secondly in drawing on various theoretical frameworks. Both quantitative and qualitative research informed the findings of the book

Developing reproducible bioinformatics analysis workflows for heterogeneous computing environments to support African genomics

Background: The Pan-African bioinformatics network, H3ABioNet, comprises 27 research institutions in 17 African countries. H3ABioNet is part of the Human Health and Heredity in Africa program (H3Africa), an African-led research consortium funded by the US National Institutes of Health and the UK Wellcome Trust, aimed at using genomics to study and improve the health of Africans. A key role of H3ABioNet is to support H3Africa projects by building bioinformatics infrastructure such as portable and reproducible bioinformatics workflows for use on heterogeneous African computing environments. Processing and analysis of genomic data is an example of a big data application requiring complex interdependent data analysis workflows. Such bioinformatics workflows take the primary and secondary input data through several computationally-intensive processing steps using different software packages, where some of the outputs form inputs for other steps. Implementing scalable, reproducible, portable and easy-to-use workflows is particularly challenging. Results: H3ABioNet has built four workflows to support (1) the calling of variants from high-throughput sequencing data; (2) the analysis of microbial populations from 16S rDNA sequence data; (3) genotyping and genome-wide association studies; and (4) single nucleotide polymorphism imputation. A week-long hackathon was organized in August 2016 with participants from six African bioinformatics groups, and US and European collaborators. Two of the workflows are built using the Common Workflow Language framework (CWL) and two using Nextflow. All the workflows are containerized for improved portability and reproducibility using Docker, and are publicly available for use by members of the H3Africa consortium and the international research community. Conclusion: The H3ABioNet workflows have been implemented in view of offering ease of use for the end user and high levels of reproducibility and portability, all while following modern state of the art bioinformatics data processing protocols. The H3ABioNet workflows will service the H3Africa consortium projects and are currently in use. All four workflows are also publicly available for research scientists worldwide to use and adapt for their respective needs. The H3ABioNet workflows will help develop bioinformatics capacity and assist genomics research within Africa and serve to increase the scientific output of H3Africa and its Pan-African Bioinformatics Network

Sustainable housing development : a City of Cape Town project evaluation

Thesis (MPA)--Stellenbosch University, 2013.ENGLISH ABSTRACT: The thesis reports on an evaluative study of the sustainability of housing development by the City of Cape Town with the Witsand, Atlantis, housing project as case study to empirically measure such sustainability. The study was attempted to determine how the City of Cape Town has planned for and implemented sustainability measures and what the results were in the Witsand project. The research therefore determined to what extent the expressed policy intent of sustainability housing delivery was implemented successfully in Witsand in terms of output and outcomes. The objectives of this study included outlining a theoretical and analytical framework for sustainable development as prescribed in the National, Provincial and Local Government policies and relevant legislation. An evaluative case study is provided, describing how the City of Cape Town implemented its policy in practice. This housing project was chosen because it is claimed to be the first large-scale integrated sustainable housing project in South Africa. The research methodology entailed an analysis of relevant literature, policies, legislation and project design documentation. In addition, the field work utilised a semi-structured mixed questionnaire for conducting interviews with the Project Manager, community development worker and a sample of residents. The research found that the City of Cape has followed the sustainability blueprint as far as their means allowed. The satisfaction level of the community is high. It was found, however, that the people, even though they received houses that were designed and constructed to take full advantage of the environment without harming it; lack the knowledge to maintain sustainable, energy conserving living. This indicates that sustainability in low income housing is not only a matter of design and technology, but also of instilling a particular behaviour amongst beneficiaries.AFRIKAANSE OPSOMMING: Hierdie tesis voer ‘n evaluering studie van die volhoubaarheid van behuising deur die Stad Kaapstad by die Witsand, Atlantis projek, wat as ‘n gevallestudie om sodanige volhoubaarheid empiries te meet, gedien het. Die studie is onderneem om te bepaal hoe die Stad Kaapstad volhoubaarheidsmaatreëls beplan en geïmplementeer het, en wat die resultate van die Witsand projek was. Die navorsing het dus bepaal tot watter mate die uitdruklike beleidsvoornemens vir die lewering van volhoubare huisverskaffing in terme van uitset en uitkomste suksesvol in Witsand geïmplementeer is. Die doelstellings van hierdie studie het die skets van ‘n teoretiese en analitiese raamwerk vir volhoubare ontwikkeling, soos in Nasionale, Provinsiale en Plaaslike beleid en toepaslike wetgewing voorgeskryf, ingesluit. ‘n Evaluerende gevallestudie wat beskrywe hoe die Stad Kaapstad se beleid prakties uitgevoer is, word voorsien. Hierdie projek is gekies vanweë die aanspraak dat dit die eerste grootskaalse geïntegreerde volhoubare projek vir huisverskaffing in Suid-Afrika was. Die navorsingsmetodologie het ‘n ontleding van toepaslike literatuur, beleid, wetgewing en gedokumenteerde projekontwerp behels. Daarbenewens het die veldwerk gebruik gemaak van ’n gemengde semi-gestruktureerde vraelys vir onderhoude met die Projekbestuurder, gemeenskapsontwikkeling werker en ‘n steekproef van die inwoners. Die navorsing het bevind dat die Stad Kaapstad die bloudruk vir volhoubaarheid sover as die stad se middele kon toelaat, gevolg het. Die bevredigingsvlak van die gemeenskap is hoog. Daar is egter gevind dat die mense, ten spyte daarvan dat hulle van huise voorsien is wat ontwerp en gebou is om sonder enige skade aan die omgewing ten volle daaruit voordeel te trek, kennis ontbreek om op volhoubare wyse en met besparing van energie te lewe. Dit dui daarop dat volhoubaarheid in lae-inkomste behuising nie maar net ‘n kwessie van ontwerp en tegnologie is nie, maar ook vereis dat ‘n bepaalde soort gedrag onder die begunstigdes gevestig moet word

The Hsp40 proteins of Plasmodium falciparum and other apicomplexa: regulating chaperone power in the parasite and the host

Extensive structural and functional remodelling of Plasmodium falciparum (malaria)-infected erythrocytes follows the export of a range of proteins of parasite origin (exportome) across the parasitophorous vacuole into the host erythrocyte. The genome of P. falciparum encodes a diverse chaperone complement including at least 43 members of the heat shock protein 40 kDa (Hsp40) family, and six members of the heat shock protein 70 kDa (Hsp70) family. Nearly half of the Hsp40 proteins of P. falciparum are predicted to contain a PEXEL/HT (Plasmodium export element/host targeting signal) sequence motif, and hence are likely to be part of the exportome. In this review we critically evaluate the classification, sequence similarity and clustering, and possible interactors of the P. falciparum Hsp40 chaperone machinery. In addition to the types I, II and III Hsp40 proteins all exhibiting the signature J-domain, the P. falciparum genome also encodes a number of specialized Hsp40 proteins with a J-like domain, which we have categorized as type IV Hsp40 proteins. Analysis of the potential P. falciparum Hsp40 protein interaction network revealed connections predominantly with cytoskeletal and membrane proteins, transcriptional machinery, DNA repair and replication machinery, translational machinery, the proteasome and proteolytic enzymes, and enzymes involved in cellular physiology. Comparison of the Hsp40 proteins of P. falciparum to those of other apicomplexa reveals that most of the proteins (especially the PEXEL/HT-containing proteins) are unique to P. falciparum. Furthermore, very few of the P. falciparum Hsp40 proteins have human homologs, except for those proteins implicated in fundamental biological processes. Our analysis suggests that P. falciparum has evolved an expanded and specialized Hsp40 protein machinery to enable it successfully to invade and remodel the human erythrocyte, and we propose a model in which these proteins are involved in chaperone-mediated translocation, folding, assembly and regulation of parasite and host proteins

Structure-function study of a Plasmodium falciparum Hsp70 using three dimensional modelling and in Vitro analyses

The spatial orientation of domains of the heat shock protein 70 from Plasmodium falciparum (PfHsp70) were mapped based on a three-dimensional model of the protein. Purified PfHsp70 displayed chaperone activity in vitro. Amino acid substitutions introduced in the chaperone's substrate binding cavity compromised the protein's chaperone function

Repeats expansions in ATXN2, NOP56, NIPA1 and ATXN1 are not associated with ALS in Africans

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized primarily by progressive loss of motor neurons. Although ALS occurs worldwide and the frequency and spectrum of identifiable genetic causes of disease varies across populations, very few studies have included African subjects. In addition to a hexanucleotide repeat expansion (RE) in C9orf72, the most common genetic cause of ALS in Europeans, REs in ATXN2, NIPA1 and ATXN1 have shown variable associations with ALS in Europeans. Intermediate range expansions in some of these genes (e.g. ATXN2) have been reported as potential risk factors, or phenotypic modifiers, of ALS. Pathogenic expansions in NOP56 cause spinocerebellar ataxia-36, which can present with prominent motor neuron degeneration. Here we compare REs in these genes in a cohort of Africans with ALS and population controls using whole genome sequencing data. Targeting genotyping of short tandem repeats at known loci within ATXN2, NIPA1, ATXN1 and NOP56 was performed using ExpansionHunter software in 105 Southern African (SA) patients with ALS. African population controls were from an in-house SA population control database (n = 25), the SA Human Genome Program (n = 24), the Simons Genome Diversity Project (n = 39) and the Illumina Polaris Diversity Cohort (IPDC) dataset (n = 50). We found intermediate RE alleles in ATXN2 (27–33 repeats) and ATXN1 (33–35 repeats), and NIPA1 long alleles (≥8 repeats) were rare in Africans, and not associated with ALS (p > 0.17). NOP56 showed no expanded alleles in either ALS or controls. We also compared the differences in allele distributions between the African and n = 50 European controls (from the IPDC). There was a statistical significant difference in the distribution of the REs in the ATXN1 between African and European controls (Chi-test p  8) in Europeans vs. Africans (Fisher’s p = 0.016). The distribution of RE alleles in ATXN2 and NOP56 were similar amongst African and European controls. In conclusion, repeat expansions in ATXN2, NIPA1 and ATXN1, which showed associations with ALS in Europeans, were not replicated in Southern Africans with ALS. •No associations with ATXN2, ATXN1, NIPA1 expansion mutations, and ALS in Africans.•Repeat expansion allele distribution in ATXN1 and NIPA1 were different in Africans compared with European populations.•ALS cases with diverse genetic ancestry should included in ALS gene discovery studies

Becoming a teacher

This book disseminates original research on learning in and from practice in pre-service teacher education. Authors such as Lederman and Lederman describe the student teaching practicum (or work-integrated learning [WIL]), which is an essential component of pre-service teacher education, as the ‘elephant in the room’. These authors note that 'the capstone experience in any teacher education programme is the student teaching practicum… [a]fter all, this is where the rubber hits the road'. However, many teacher educators will agree that this WIL component is sometimes very insufficient in assisting the student teacher to develop their own footing and voice as a teacher. This is the ‘gap’ that this research book addresses. Most of the chapters in the book report empirical data, with the exception of two chapters that can be categorized as systematic reviews. WIL is addressed from various angles in the chapters. Chapter 6 focuses on research related to what makes Finnish teacher education so effective, and in Chapter 4 researchers of the University of Johannesburg disseminate their findings on establishing a teaching school (based on Finnish insights) in Johannesburg. Chapter 3 highlights the challenges faced in open-and distance learning teacher education contexts. Several of the chapters disseminate research findings on alternative interventions to classic WIL, namely, where “safe spaces” or laboratories are created for student teachers to learn and grow professionally. These could either be simulations, such as software programmes and avatars in the intervention described in Chapter 2; student excursions, as the findings in chapters 5, 7 and 10 portray; or alternative approaches to WIL (e.g. Chapters 11 and 12). The book is devoted to scholarship in the field of pre-service teacher education. The target audience is scholars working in the fields of pre-service teacher education, work-integrated learning, and self-directed learning. The book makes a unique contribution in terms of firstly its extensive use of Cultural-Historical Activity Theory as a research lens, and secondly in drawing on various theoretical frameworks. Both quantitative and qualitative research informed the findings of the book