ORCID Profile
0000-0001-5629-1175
Current Organisations
University of Glasgow
,
University of Melbourne
,
University of Aberdeen
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Biochemistry and Cell Biology | Protein Trafficking | Cell Development, Proliferation and Death | Biomechanical Engineering | Plant Biology | Signal Transduction | Biochemistry and Cell Biology not elsewhere classified | Biological Physics | Global Change Biology | Infectious Agents | Cellular Interactions (incl. Adhesion, Matrix, Cell Wall) | Plant Cell and Molecular Biology | Immunology | Cellular Immunology | Medical Parasitology | Nanobiotechnology |
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Biological Sciences | Plant Production and Plant Primary Products not elsewhere classified | Nervous System and Disorders | Production of Biofuels (Biomass) | Expanding Knowledge in Technology | Climate and Climate Change not elsewhere classified | Expanding Knowledge in Engineering | Health not elsewhere classified | Immune System and Allergy | Infectious Diseases
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Publications
Uracil misincorporation in human DNA detected using single cell gel electrophoresis
Publisher: Oxford University Press (OUP)
Date: 09-1997
Abstract: Poor folate status may be important in the aetiology of several epithelial cell malignancies including cancer of the uterine cervix. Folic acid is essential in the synthesis of purine nucleotides and the pyrimidine nucleoside thymidine and it is probable that imbalances in these DNA precursors negatively effect DNA stability and may ultimately lead to malignant transformation. The development of a modified 'comet assay' using the bacterial DNA repair enzyme uracil DNA glycosylase, to detect misincorporated uracil in human DNA is reported here. The effect of perturbing folic acid and deoxyuridine levels on uracil misincorporation in normal human lymphocytes and cultured human tumour cells was investigated using this assay. HeLa cells and peripheral human lymphocytes incubated as agarose-embedded nucleoids, with 1 unit of uracil DNA glycosylase per microg of DNA, contained low levels of uracil in their DNA. Both HeLa cells and stimulated human lymphocytes cultured in folate-deficient medium were growth arrested. Incubating human lymphocytes in folate-deficient medium significantly increased the level of uracil detected compared with control cells. HeLa cells showed an increase in non-specific DNA damage (strand breaks). Deoxyuridine (100 microM) significantly increased the level of uracil detected in the DNA of both folate-deficient and control HeLa cells. It appears that this modified comet assay specifically detects misincorporated uracil in single human cells. It should, therefore, prove valuable in determining the role of folic acid status in DNA instability and cancer.
Targeted mutagenesis of the ring‐exported protein‐1 of Plasmodium falciparum disrupts the architecture of Maurer's cleft organelles
Publisher: Wiley
Date: 23-07-2008
DOI: 10.1111/J.1365-2958.2008.06329.X
Abstract: Mature red blood cells have no internal trafficking machinery, so the intraerythrocytic malaria parasite, Plasmodium falciparum, establishes its own transport system to export virulence factors to the red blood cell surface. Maurer's clefts are parasite-derived membranous structures that form an important component of this exported secretory system. A protein with sequence similarity to a Golgi tethering protein, referred to as ring-exported protein-1 (REX1), is associated with Maurer's clefts. A REX1-GFP chimera is trafficked to the Maurer's clefts and preferentially associates with the edges of these structures, as well as with vesicle-like structures and with stalk-like extensions that are involved in tethering the Maurer's clefts to other membranes. We have generated transfected P. falciparum expressing REX1 truncations or deletion. Electron microscopy reveals that the Maurer's clefts of REX1 truncation mutants have stacked cisternae, while the 3D7 parent line has unstacked Maurer's clefts. D10 parasites, which have lost the right end of chromosome 9, including the rex1 gene, also display Maurer's clefts with stacked cisternae. Expression of full-length REX1-GFP in D10 parasites restores the 3D7-type unstacked Maurer's cleft phenotype. These studies reveal the importance of the REX1 protein in determining the ultrastructure of the Maurer's cleft system.
The Apical Complex Provides a Regulated Gateway for Secretion of Invasion Factors in Toxoplasma
Publisher: Public Library of Science (PLoS)
Date: 17-04-2014
The Golgi ribbon in mammalian cells negatively regulates autophagy by modulating mTOR activity.
Publisher: The Company of Biologists
Date: 2018
DOI: 10.1242/JCS.211987
Abstract: In vertebrates, in idual Golgi stacks are joined into a compact ribbon structure, however, the relevance of a ribbon structure has been elusive. Here we exploit the finding that the membrane tether of the trans-Golgi network, GCC88, regulates the balance between Golgi mini-stacks and the Golgi ribbon. Loss of Golgi ribbons in stable cells overexpressing GCC88 resulted in compromised mechanistic target of rapamycin (mTOR) signaling and a dramatic increase in LC3-II-positive autophagosomes, whereas RNAi depletion of GCC88 restored a Golgi ribbon and reduced autophagy. mTOR was absent from dispersed Golgi mini-stacks whereas recruitment of mTOR to lysosomes was unaffected. We show that the Golgi ribbon is a site for localization and activation of mTOR, a process dependent on the ribbon structure. We demonstrate a strict temporal sequence of fragmentation of Golgi ribbon, loss of Golgi mTOR followed by increased autophagy. Golgi ribbon fragmentation has been reported in various neurodegenerative diseases and we demonstrate the potential relevance of our findings in neuronal cells using a model of neurodegeneration. Overall, this study highlights a role for the Golgi ribbon in pathways central to cellular homeostasis.
Cellular architecture of Plasmodium falciparum-infected erythrocytes
Publisher: Elsevier BV
Date: 08-2010
DOI: 10.1016/J.IJPARA.2010.04.012
Abstract: Plasmodium falciparum is a protozoan parasite that is responsible for the most pathogenic form of human malaria. The particular virulence of this parasite derives from its ability to develop within the erythrocytes of its host and to subvert their function. The intraerythrocytic parasite devours haemoglobin, and remodels its host cell to cause adhesion to blood vessel walls. Ultrastructural studies of P. falciparum have played a major role in defining its cell architecture and in resolving cell biology controversies. Here we review some of the early studies and describe some recent developments in electron microscopy techniques that have revealed information about the organization of the parasite in the blood stage of development. We present images of P. falciparum at different stages of the life cycle and highlight some of the plasmodium-specific organelles, the haemoglobin digestive apparatus and the membrane structures that are elaborated in the host cell cytoplasm to traffic virulence proteins to the erythrocyte surface. We describe methods for whole cell ultrastructural imaging that can provide three-dimensional views of intraerythrocytic development.
Glucagon-like peptide 1 and peptide YY are in separate storage organelles in enteroendocrine cells
Publisher: Springer Science and Business Media LLC
Date: 20-05-2014
DOI: 10.1007/S00441-014-1886-9
Abstract: A sub-group of enteroendocrine cells (L cells) release gastrointestinal hormones, GLP-1 and PYY, which have different but overlapping physiological effects, in response to intraluminal nutrients. Whilst their release profiles are not identical, how the plasma levels of these two hormones are differentially regulated is not well understood. We investigate the possibility that GLP-1 and PYY are in separate storage vesicles. In this study, the subcellular location of GLP-1 and PYY storage organelles is investigated using double-labelling immunohistochemistry, super resolution microscopy and high-resolution confocal microscopy. In all species tested, human, pig, rat and mouse, most cytoplasmic stores that exhibited GLP-1 or PYY immunofluorescence were distinct from each other. The volume occupancy, determined by 3D analysis, overlapped by only about 10∼20 %. At the lower resolution achieved by conventional confocal microscopy, there was also evidence of GLP-1 and PYY being in separate storage compartments but, in subcellular regions where there were many storage vesicles, separate storage could not be resolved. The results indicate that different storage vesicles in L cells contain predominantly GLP-1 or predominantly PYY. Whether GLP-1 and PYY storage vesicles are selectively mobilised and their products are selectively released needs to be determined.
The knob protein KAHRP assembles into a ring-shaped structure that underpins virulence complex assembly.
Publisher: Public Library of Science (PLoS)
Date: 09-05-2019
Differential use of autophagy by primary dendritic cells specialized in cross-presentation
Publisher: Informa UK Limited
Date: 07-05-2015
Plasmodium falciparum formins are essential for invasion and sexual stage development
Publisher: Springer Science and Business Media LLC
Date: 18-08-2023
DOI: 10.1038/S42003-023-05233-Y
Abstract: The malaria parasite uses actin-based mechanisms throughout its lifecycle to control a range of biological processes including intracellular trafficking, gene regulation, parasite motility and invasion. In this work we assign functions to the Plasmodium falciparum formins 1 and 2 (FRM1 and FRM2) proteins in asexual and sexual blood stage development. We show that FRM1 is essential for merozoite invasion and FRM2 is required for efficient cell ision. We also observed ergent functions for FRM1 and FRM2 in gametocyte development. Conditional deletion of FRM1 leads to a delay in gametocyte stage progression. We show that FRM2 controls the actin and microtubule cytoskeletons in developing gametocytes, with premature removal of the protein resulting in a loss of transmissible stage V gametocytes. Lastly, we show that targeting formin proteins with the small molecule inhibitor of formin homology domain 2 (SMIFH2) leads to a multistage block in asexual and sexual stage parasite development.
A female gametocyte-specific ABC transporter plays a role in lipid metabolism in the malaria parasite
Publisher: Springer Science and Business Media LLC
Date: 08-09-2014
DOI: 10.1038/NCOMMS5773
Abstract: ATP-binding cassette (ABC) transporters serve a variety of physiological functions as well as play key roles in drug resistance. The genome of the human malaria parasite, Plasmodium falciparum, encodes multiple members of this family, one of which, gABCG2, is transcribed predominantly in the gametocyte stage. Here we use gene deletion and tagging to investigate the expression, localization and function of gABCG2. The protein is found in a single dot-like lipid-rich structure within female, but not male, gametocytes. gABCG2-knockout cell lines produce more gametocytes of both sexes. By contrast, cholesteryl esters, diacylglycerols and triacylglycerols are significantly reduced in gABCG2-knockout gametocyte stages. We propose a role for gABCG2 in the regulation of gametocyte numbers and in the accumulation of neutral lipids, which are likely important for parasite development in the insect stages of the parasite life cycle.
Viral regulation of host cell biology by hijacking of the nucleolar DNA-damage response.
Publisher: Springer Science and Business Media LLC
Date: 03-08-2018
DOI: 10.1038/S41467-018-05354-7
Abstract: Recent studies indicate that nucleoli play critical roles in the DNA-damage response (DDR) via interaction of DDR machinery including NBS1 with nucleolar Treacle protein, a key mediator of ribosomal RNA (rRNA) transcription and processing. Here, using proteomics, confocal and single molecule super-resolution imaging, and infection under biosafety level-4 containment, we show that this nucleolar DDR pathway is targeted by infectious pathogens. We find that the matrix proteins of Hendra virus and Nipah virus, highly pathogenic viruses of the Henipavirus genus in the order Mononegavirales , interact with Treacle and inhibit its function, thereby silencing rRNA biogenesis, consistent with mimicking NBS1–Treacle interaction during a DDR. Furthermore, inhibition of Treacle expression/function enhances henipavirus production. These data identify a mechanism for viral modulation of host cells by appropriating the nucleolar DDR and represent, to our knowledge, the first direct intranucleolar function for proteins of any mononegavirus.
Targeting of microvillus protein Eps8 by the NleH effector kinases from enteropathogenic E. coli
Publisher: Proceedings of the National Academy of Sciences
Date: 17-08-2022
Abstract: Attaching and effacing (AE) lesion formation on enterocytes by enteropathogenic Escherichia coli (EPEC) requires the EPEC type III secretion system (T3SS). Two T3SS effectors injected into the host cell during infection are the atypical kinases, NleH1 and NleH2. However, the host targets of NleH1 and NleH2 kinase activity during infection have not been reported. Here phosphoproteomics identified Ser775 in the microvillus protein Eps8 as a bona fide target of NleH1 and NleH2 phosphorylation. Both kinases interacted with Eps8 through previously unrecognized, noncanonical “proline-rich” motifs, PxxDY, that bound the Src Homology 3 (SH3) domain of Eps8. Structural analysis of the Eps8 SH3 domain bound to a peptide containing one of the proline-rich motifs from NleH showed that the N-terminal part of the peptide adopts a type II polyproline helix, and its C-terminal “DY” segment makes multiple contacts with the SH3 domain. Ser775 phosphorylation by NleH1 or NleH2 hindered Eps8 bundling activity and drove dispersal of Eps8 from the AE lesion during EPEC infection. This finding suggested that NleH1 and NleH2 altered the cellular localization of Eps8 and the cytoskeletal composition of AE lesions during EPEC infection.
Organization and function of an actin cytoskeleton inPlasmodium falciparumgametocytes
Publisher: Hindawi Limited
Date: 31-10-2014
DOI: 10.1111/CMI.12359
Abstract: In preparation for transmission to its mosquito vector, Plasmodium falciparum, the most virulent of the human malaria parasites, adopts an unusual elongated shape. Here we describe a previously unrecognized actin-based cytoskeleton that is assembled in maturing P. falciparum gametocytes. Differential extraction reveals the presence of a highly stabilized population of F-actin at all stages of development. Super-resolution microscopy reveals an F-actin cytoskeleton that is concentrated at the ends of the elongating gametocyte but extends inward along the microtubule cytoskeleton. Formin-1 is also concentrated at the gametocyte ends suggesting a role in actin stabilization. Immunoelectron microscopy confirms that the actin cytoskeleton is located under the inner membrane complex rather than in the sub-alveolar space. In stage V gametocytes, the actin and microtubule cytoskeletons are reorganized in a coordinated fashion. The actin-depolymerizing agent, cytochalasin D, depletes actin from the end of the gametocytes, whereas the actin-stabilizing compound, jasplakinolide, induces formation of large bundles and prevents late-stage disassembly of the actin cytoskeleton. Long-term treatment with these compounds is associated with disruption of the normal mitochondrial organization and decreased gametocyte viability.
Determination of protein subcellular localization in apicomplexan parasites
Publisher: Elsevier BV
Date: 12-2012
Abstract: Parasites from the phylum Apicomplexa include causative agents of serious diseases including malaria (Plasmodium spp.) and toxoplasmosis (Toxoplasma gondii). Apicomplexan parasites infect thousands of types of animal cells and send their proteins to an array of compartments within their own cell, as well as exporting proteins into and beyond their host cell. Ascertaining destinations to which in idual proteins are delivered allows researchers to better understand parasite biology and to identify potential targets for therapeutic interventions. Our toolkit for establishing subcellular locations of apicomplexan proteins is becoming more extensive and specialized, and here we review developments in this technology.
Interactions between Cellulose and (1,3;1,4)-β-glucans and Arabinoxylans in the Regenerating Wall of Suspension Culture Cells of the Ryegrass Lolium multiflorum
Publisher: MDPI AG
Date: 11-01-2021
Abstract: Plant cell walls (PCWs) form the outer barrier of cells that give the plant strength and directly interact with the environment and other cells in the plant. PCWs are composed of several polysaccharides, of which cellulose forms the main fibrillar network. Enmeshed between these fibrils of cellulose are non-cellulosic polysaccharides (NCPs), pectins, and proteins. This study investigates the sequence, timing, patterning, and architecture of cell wall polysaccharide regeneration in suspension culture cells (SCC) of the grass species Lolium multiflorum (Lolium). Confocal, superresolution, and electron microscopies were used in combination with cytochemical labeling to investigate polysaccharide deposition in SCC after protoplasting. Cellulose was the first polysaccharide observed, followed shortly thereafter by (1,3 ,4)-β-glucan, which is also known as mixed-linkage glucan (MLG), arabinoxylan (AX), and callose. Cellulose formed fibrils with AX and produced a filamentous-like network, whereas MLG formed punctate patches. Using colocalization analysis, cellulose and AX were shown to interact during early stages of wall generation, but this interaction reduced over time as the wall matured. AX and MLG interactions increased slightly over time, but cellulose and MLG were not seen to interact. Callose initially formed patches that were randomly positioned on the protoplast surface. There was no consistency in size or location over time. The architecture observed via superresolution microscopy showed similarities to the biophysical maps produced using atomic force microscopy and can give insight into the role of polysaccharides in PCWs.
Plasmodium falciparum possesses organelle-specific α-keto acid dehydrogenase complexes and lipoylation pathways
Publisher: Portland Press Ltd.
Date: 10-2005
DOI: 10.1042/BST20050977
From Sequence to Chromosome: The Tip of the X Chromosome of D. melanogaster
Publisher: American Association for the Advancement of Science (AAAS)
Date: 24-03-2000
DOI: 10.1126/SCIENCE.287.5461.2220
Abstract: One of the rewards of having a Drosophila melanogaster whole-genome sequence will be the potential to understand the molecular bases for structural features of chromosomes that have been a long-standing puzzle. Analysis of 2.6 megabases of sequence from the tip of the X chromosome of Drosophila identifies 273 genes. Cloned DNAs from the characteristic bulbous structure at the tip of the X chromosome in the region of the broad complex display an unusual pattern of in situ hybridization. Sequence analysis revealed that this region comprises 154 kilobases of DNA flanked by 1.2-kilobases of inverted repeats, each composed of a 350–base pair satellite related element. Thus, some aspects of chromosome structure appear to be revealed directly within the DNA sequence itself.
Complementation in trans of Porphyromonas gingivalis Lipopolysaccharide Biosynthetic Mutants Demonstrates Lipopolysaccharide Exchange.
Publisher: American Society for Microbiology
Date: 21-04-2021
DOI: 10.1128/JB.00631-20
Abstract: Porphyromonas gingivalis is a keystone pathogen contributing to periodontitis in humans, leading to tooth loss. The oral microbiota is essential in this pathogenic process and changes from predominantly Gram-positive (health) to predominantly Gram-negative (disease) species. P. gingivalis uses its type IX secretion system (T9SS) to secrete and conjugate virulence proteins to anionic lipopolysaccharide (A-LPS).
Role of Plasmodium falciparum Protein GEXP07 in Maurer's Cleft Morphology, Knob Architecture, and P. falciparum EMP1 Trafficking.
Publisher: American Society for Microbiology
Date: 28-04-2020
Abstract: The trafficking of the virulence antigen Pf EMP1 and its presentation at the knob structures at the surface of parasite-infected RBCs are central to severe adhesion-related pathologies such as cerebral and placental malaria. This work adds to our understanding of how PfEMP1 is trafficked to the RBC membrane by defining the protein-protein interaction networks that function at the Maurer’s clefts controlling PfEMP1 loading and unloading. We characterize a protein needed for virulence protein trafficking and provide new insights into the mechanisms for host cell remodeling, parasite survival within the host, and virulence.
Disrupting assembly of the inner membrane complex blocks Plasmodium falciparum sexual stage development.
Publisher: Public Library of Science (PLoS)
Date: 06-10-2017
Structured illumination microscopy reveals actin I localization in discreet foci in Plasmodium berghei gametocytes
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.EXPPARA.2017.08.001
Abstract: Actin has important roles in Plasmodium parasites but its exact function in different life stages is not yet fully elucidated. Here we report the localization of ubiquitous actin I in gametocytes of the rodent model parasite P. berghei. Using an antibody specifically recognizing F-actin and deconvolution microscopy we detected actin I in a punctate pattern in gametocytes. 3D-Structured Illumination Microscopy which allows sub-diffraction limit imaging resolved the signal into structures of less than 130 nm length. A portion of actin I was soluble, but the protein was also found complexed in a stabilized form which could only be completely solubilized by treatment with SDS. An additional population of actin was pelleted at 100 000 × g, consistent with F-actin. Our results suggest that actin in this non-motile form of the parasite is present in short filaments cross-linked to other structures in a cytoskeleton.
Renal participation of myeloperoxidase in antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis
Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1038/KI.2015.202
Abstract: Myeloperoxidase (MPO) is an important neutrophil lysosomal enzyme, a major autoantigen, and a potential mediator of tissue injury in MPO-ANCA-associated vasculitis (MPO-AAV) and glomerulonephritis. Here we examined MPO deposition in kidney biopsies from 47 patients with MPO-AAV. Leukocyte accumulation and fibrin deposition consistent with cell-mediated immunity was a major feature. Tubulointerstitial macrophage, CD4+ and CD8+ T-cell, and neutrophil numbers correlated with low presenting eGFR. MPO was not detected in kidneys from patients with minimal change or thin basement membrane disease, but was prominent in glomerular, periglomerular, and tubulointerstitial regions in MPO-AAV. Extracellular MPO released from leukocytes was pronounced in all MPO-AAV patients. Similar numbers of neutrophils and macrophages expressed MPO in the kidneys, but colocalization studies identified neutrophils as the major source of extracellular MPO. Extraleukocyte MPO was prominent in neutrophil extracellular traps in the majority of patients most of which had traps in half or more glomeruli. These traps were associated with more neutrophils and more MPO within glomeruli. Glomerular MPO-containing macrophages generated extracellular trap-like structures. MPO also localized to endothelial cells and podocytes. The presence of the most active glomerular lesions (both segmental necrosis and cellular crescents) correlated with intraglomerular CD4+ cells and MPO+ macrophages. Thus, cellular and extracellular MPO may cause glomerular and interstitial injury.
Paraspeckle subnuclear bodies depend on dynamic heterodimerisation of DBHS RNA-binding proteins via their structured domains
Publisher: Elsevier BV
Date: 11-2022
Sustained subcutaneous delivery of secretome of human cardiac stem cells promotes cardiac repair following myocardial infarction
Publisher: Oxford University Press (OUP)
Date: 06-04-2021
DOI: 10.1093/CVR/CVAA088
Abstract: To establish pre-clinical proof of concept that sustained subcutaneous delivery of the secretome of human cardiac stem cells (CSCs) can be achieved in vivo to produce significant cardioreparative outcomes in the setting of myocardial infarction. Rats were subjected to permanent ligation of left anterior descending coronary artery and randomized to receive subcutaneous implantation of TheraCyte devices containing either culture media as control or 1 × 106 human W8B2+ CSCs, immediately following myocardial ischaemia. At 4 weeks following myocardial infarction, rats treated with W8B2+ CSCs encapsulated within the TheraCyte device showed preserved left ventricular ejection fraction. The preservation of cardiac function was accompanied by reduced fibrotic scar tissue, interstitial fibrosis, cardiomyocyte hypertrophy, as well as increased myocardial vascular density. Histological analysis of the TheraCyte devices harvested at 4 weeks post-implantation demonstrated survival of human W8B2+ CSCs within the devices, and the outer membrane was highly vascularized by host blood vessels. Using CSCs expressing plasma membrane reporters, extracellular vesicles of W8B2+ CSCs were found to be transferred to the heart and other organs at 4 weeks post-implantation. Furthermore, mass spectrometry-based proteomic profiling of extracellular vesicles of W8B2+ CSCs identified proteins implicated in inflammation, immunoregulation, cell survival, angiogenesis, as well as tissue remodelling and fibrosis that could mediate the cardioreparative effects of secretome of human W8B2+ CSCs. Subcutaneous implantation of TheraCyte devices encapsulating human W8B2+ CSCs attenuated adverse cardiac remodelling and preserved cardiac function following myocardial infarction. The TheraCyte device can be employed to deliver stem cells in a minimally invasive manner for effective secretome-based cardiac therapy.
Identification of Acid-Base Catalytic Residues of High-Mr Thioredoxin Reductase from Plasmodium falciparum
Publisher: Elsevier BV
Date: 11-2006
Spatial and temporal mapping of the PfEMP1 export pathway in Plasmodium falciparum
Publisher: Hindawi Limited
Date: 14-03-2013
DOI: 10.1111/CMI.12125
Decreased K13 Abundance Reduces Hemoglobin Catabolism and Proteotoxic Stress, Underpinning Artemisinin Resistance.
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.CELREP.2019.10.095
Abstract: Increased tolerance of Plasmodium falciparum to front-line artemisinin antimalarials (ARTs) is associated with mutations in Kelch13 (K13), although the precise role of K13 remains unclear. Here, we show that K13 mutations result in decreased expression of this protein, while mislocalization of K13 mimics resistance-conferring mutations, pinpointing partial loss of function of K13 as the relevant molecular event. K13-GFP is associated with ∼170 nm diameter doughnut-shaped structures at the parasite periphery, consistent with the location and dimensions of cytostomes. Moreover, the hemoglobin-peptide profile of ring-stage parasites is reduced when K13 is mislocalized. We developed a pulse-SILAC approach to quantify protein turnover and observe less disruption to protein turnover following ART exposure when K13 is mislocalized. Our findings suggest that K13 regulates digestive vacuole biogenesis and the uptake/degradation of hemoglobin and that ART resistance is mediated by a decrease in heme-dependent drug activation, less proteotoxicity, and increased survival of parasite ring stages.
Differential inhibition of high and low Mrthioredoxin reductases of parasites by organotelluriums supports the concept that low Mrthioredoxin reductases are good drug targets
Publisher: Cambridge University Press (CUP)
Date: 04-11-2008
DOI: 10.1017/S0031182008005131
Abstract: Thioredoxin reductase (TrxR), a NADPH-dependent disulfide oxidoreductase, is vital in numerous cellular processes including defence against reactive oxygen species, cell proliferation and signal transduction. TrxRs occur in 2 forms, a high M r enzyme characterized by those of mammals, the malaria parasite Plasmodium falciparum and some worms, and a low M r form is present in bacteria, fungi, plants and some protozoan parasites. Our hypothesis is that the differences between the forms can be exploited in the development of selective inhibitors. In this study, cyclodextrin- and sulfonic acid-derived organotelluriums known to inhibit mammalian TrxR were investigated for their relative efficacy against P. falciparum TrxR ( Pf TrxR), a high M r enzyme, and Trichomonas vaginalis TrxR ( Tv TrxR), a low M r form of TrxR. The results suggest that selective inhibition of low M r TrxRs is a feasible goal.
Super-resolution optical imaging of binary colloidal assemblies
Publisher: Inderscience Publishers
Date: 2014
Detailed morphological characterisation of Hendra virus infection of different cell types using super-resolution and conventional imaging
Publisher: Springer Science and Business Media LLC
Date: 27-11-2014
From First Base: The Sequence of the Tip of the X Chromosome of Drosophila melanogaster, a Comparison of Two Sequencing Strategies
Publisher: Cold Spring Harbor Laboratory
Date: 05-2001
DOI: 10.1101/GR.173801
Abstract: We present the sequence of a contiguous 2.63 Mb of DNA extending from the tip of the X chromosome of Drosophila melanogaster. Within this sequence, we predict 277 protein coding genes, of which 94 had been sequenced already in the course of studying the biology of their gene products, and ex les of 12 different transposable elements. We show that an interval between bands 3A2 and 3C2, believed in the 1970s to show a correlation between the number of bands on the polytene chromosomes and the 20 genes identified by conventional genetics, is predicted to contain 45 genes from its DNA sequence. We have determined the insertion sites of P-elements from 111 mutant lines, about half of which are in a position likely to affect the expression of novel predicted genes, thus representing a resource for subsequent functional genomic analysis. We compare the European Drosophila Genome Project sequence with the corresponding part of the independently assembled and annotated Joint Sequence determined through “shotgun” sequencing. Discounting differences in the distribution of known transposable elements between the strains sequenced in the two projects, we detected three major sequence differences, two of which are probably explained by errors in assembly the origin of the third major difference is unclear. In addition there are eight sequence gaps within the Joint Sequence. At least six of these eight gaps are likely to be sites of transposable elements the other two are complex. Of the 275 genes in common to both projects, 60% are identical within 1% of their predicted amino-acid sequence and 31% show minor differences such as in choice of translation initiation or termination codons the remaining 9% show major differences in interpretation. [All of the sequences analyzed in this paper have been deposited in the EMBL-Bank database under the following accession nos.: AL009146 , AL009147 , AL009171 , AL009188 – AL009196 , AL021067 , AL021086 , AL021106 – AL021108 , AL021726 , AL021728 , AL022017 , AL022018 , AL022139 , AL023873 , AL023874 , AL023893 , AL024453 , AL024455 – AL024457 , AL024485 , AL030993 , AL030994 , AL031024 – AL031028 , AL031128 , AL031173 , AL031366 , AL031367 , AL031581 – AL031583 , AL031640 , AL031765 , AL031883 , AL031884 , AL034388 , AL034544 , AL035104 , AL035105 , AL035207 , AL035245 , AL035331 , AL035632 , AL049535 , AL050231 , AL050232 , AL109630 , AL121804 , AL121806 , AL132651 , AL132792 , AL132797 , AL133503 – AL133506 , AL138678 , AL138971 , AL138972 , and Z98269 . A single file ( FASTA format) of the 2.6-Mb contig is available from ftp://ftp.ebi.ac.uk ub/databases/edgp/contigs/contig_1.fa .]
Genetic ablation of a Maurer's cleft protein prevents assembly of the Plasmodium falciparum virulence complex
Publisher: Wiley
Date: 07-07-2011
DOI: 10.1111/J.1365-2958.2011.07740.X
Abstract: The malaria parasite Plasmodium falciparum assembles knob structures underneath the erythrocyte membrane that help present the major virulence protein, P. falciparum erythrocyte membrane protein-1 (PfEMP1). Membranous structures called Maurer's clefts are established in the erythrocyte cytoplasm and function as sorting compartments for proteins en route to the RBC membrane, including the knob-associated histidine-rich protein (KAHRP), and PfEMP1. We have generated mutants in which the Maurer's cleft protein, the ring exported protein-1 (REX1) is truncated or deleted. Removal of the C-terminal domain of REX1 compromises Maurer's cleft architecture and PfEMP1-mediated cytoadherance but permits some trafficking of PfEMP1 to the erythrocyte surface. Deletion of the coiled-coil region of REX1 ablates PfEMP1 surface display, trapping PfEMP1 at the Maurer's clefts. Complementation of mutants with REX1 partly restores PfEMP1-mediated binding to the endothelial cell ligand, CD36. Deletion of the coiled-coil region or complete deletion of REX1 is tightly associated with the loss of a subtelomeric region of chromosome 2, encoding KAHRP and other proteins. A KAHRP-green fluorescent protein (GFP) fusion expressed in the REX1-deletion parasites shows defective trafficking. Thus, loss of functional REX1 directly or indirectly ablates the assembly of the P. falciparum virulence complex at the surface of host erythrocytes.
Super-resolution optical imaging of malaria parasites
Publisher: IEEE
Date: 08-2011
Essential role of Plasmodium perforin-like protein 4 in ookinete midgut passage
Publisher: Public Library of Science (PLoS)
Date: 13-08-2018
Mapping and identification of essential gene functions on the X chromosome of Drosophila
Publisher: EMBO
Date: 2002
Image reconstruction for structured-illumination microscopy with low signal level
Publisher: The Optical Society
Date: 03-04-2014
DOI: 10.1364/OE.22.008687
Correction: Essential role of Plasmodium perforin-like protein 4 in ookinete midgut passage
Publisher: Public Library of Science (PLoS)
Date: 12-09-2018
Co-ordinated stage-dependent enhancement of Plasmodium falciparum antioxidant enzymes and heat shock protein expression in parasites growing in oxidatively stressed or G6PD-deficient red blood cells
Publisher: Springer Science and Business Media LLC
Date: 29-05-2009
Abstract: Plasmodium falciparum -parasitized red blood cells (RBCs) are equipped with protective antioxidant enzymes and heat shock proteins (HSPs). The latter are only considered to protect against thermal stress. Important issues are poorly explored: first, it is insufficiently known how both systems are expressed in relation to the parasite developmental stage secondly, it is unknown whether P. falciparum HSPs are redox-responsive, in view of redox sensitivity of HSP in eukaryotic cells thirdly, it is poorly known how the antioxidant defense machinery would respond to increased oxidative stress or inhibited antioxidant defense. Those issues are interesting as several antimalarials increase the oxidative stress or block antioxidant defense in the parasitized RBC. In addition, numerous inhibitors of HSPs are currently developed for cancer therapy and might be tested as anti-malarials. Thus, the joint disruption of the parasite antioxidant enzymes/HSP system would interfere with parasite growth and open new perspectives for anti-malaria therapy. Stage-dependent mRNA expression of ten representative P. falciparum antioxidant enzymes and hsp 60/70–2/70–3/75/90 was studied by quantitative real-time RT-PCR in parasites growing in normal RBCs, in RBCs oxidatively-stressed by moderate H2O2 generation and in G6PD-deficient RBCs. Protein expression of antioxidant enzymes was assayed by Western blotting. The pentosephosphate-pathway flux was measured in isolated parasites after Sendai-virus lysis of RBC membrane. In parasites growing in normal RBCs, mRNA expression of antioxidant enzymes and HSPs displayed co-ordinated stage-dependent modulation, being low at ring, highest at early trophozoite and again very low at schizont stage. Additional exogenous oxidative stress or growth in antioxidant blunted G6PD-deficient RBCs indicated remarkable flexibility of both systems, manifested by enhanced, co-ordinated mRNA expression of antioxidant enzymes and HSPs. Protein expression of antioxidant enzymes was also increased in oxidatively-stressed trophozoites. Results indicated that mRNA expression of parasite antioxidant enzymes and HSPs was co-ordinated and stage-dependent. Secondly, both systems were redox-responsive and showed remarkably increased and co-ordinated expression in oxidatively-stressed parasites and in parasites growing in antioxidant blunted G6PD-deficient RBCs. Lastly, as important anti-malarials either increase oxidant stress or impair antioxidant defense, results may encourage the inclusion of anti-HSP molecules in anti-malarial combined drugs.
A repeat sequence domain of the ring-exported protein-1 of Plasmodium falciparum controls export machinery architecture and virulence protein trafficking
Publisher: Wiley
Date: 25-09-2015
DOI: 10.1111/MMI.13201
Structural and biochemical characterization of a mitochondrial peroxiredoxin from Plasmodium falciparum
Publisher: Wiley
Date: 21-07-2006
Apicoplast Lipoic Acid Protein Ligase B Is Not Essential for Plasmodium falciparum
Publisher: Public Library of Science (PLoS)
Date: 07-12-2007
The human malaria parasite Plasmodium falciparum possesses two distinct dihydrolipoamide dehydrogenases
Publisher: Wiley
Date: 25-11-2004
DOI: 10.1111/J.1365-2958.2004.04398.X
Abstract: The Plasmodium falciparum genome contains genes encoding three alpha-ketoacid dehydrogenase multienzyme complexes (KADHs) that have central metabolic functions. The parasites possess two distinct genes encoding dihydrolipoamide dehydrogenases (LipDH), which are indispensable subunits of KADHs. This situation is reminiscent of that in plants, where two distinct LipDHs are found in mitochondria and chloroplasts, respectively, that are part of the organelle-specific KADHs. In this study, we show by reverse transcription polymerase chain reaction (RT-PCR) that the genes encoding subunits of all three KADHs, including both LipDHs, are transcribed during the erythrocytic development of P. falciparum. Protein expression of mitochondrial LipDH and mitochondrial branched chain alpha-ketoacid dihydrolipoamide transacylase in these parasite stages was confirmed by Western blotting. The localization of the two LipDHs to the parasite's apicoplast and mitochondrion, respectively, was shown by expressing the LipDH N-terminal presequences fused to green fluorescent protein in erythrocytic stages of P. falciparum and by immunofluorescent colocalization with organelle-specific markers. Biochemical characterization of recombinantly expressed mitochondrial LipDH revealed that the protein has kinetic and physicochemical characteristics typical of these flavo disulphide oxidoreductases. We propose that the mitochondrial LipDH is part of the mitochondrial alpha-ketoglutarate dehydrogenase and branched chain alpha-ketoacid dehydrogenase complexes and that the apicoplast LipDH is an integral part of the pyruvate dehydrogenase complex which occurs only in the apicoplast in P. falciparum.
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University Of Glasgow
Location: United Kingdom of Great Britain and Northern Ireland
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Location: United Kingdom of Great Britain and Northern Ireland
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