scholarly journals Plasmodium DDI1 is an essential chromatin-associated protein with a role in DNA-protein crosslink repair

2021 ◽  
Author(s):  
Nandita Tanneru ◽  
M Angel Nivya ◽  
Navin Adhikari ◽  
Kanika Saxena ◽  
Zeba Rizvi ◽  
...  
Keyword(s):  
Antimalarial Activity ◽  
Domain Architecture ◽  
Parasite Development ◽  
Major Life ◽  
Knock Down ◽  
Cellular Processes ◽  
Uba Domain ◽  
Protein Crosslinks ◽  
Increased Susceptibility ◽  
Crosslink Repair

DDI1 proteins are conserved in eukaryotes and involved in a variety of cellular processes, including proteasomal degradation of specific proteins and DNA-protein crosslink repair. All DDI1 proteins contain ubiquitin-like (UBL) and retroviral aspartyl protease (RVP) domains, and some also contain ubiquitin-associated (UBA) domain, which mediate distinct activities of these proteins. We investigated the Plasmodium DDI1 to identify its roles during parasite development and potential as a therapeutic target. The DDI1 proteins of Plasmodium and other Apicomplexan parasites vary in domain architecture, share UBL and RVP domains, and the majority of proteins contain the UBA domain. Plasmodium DDI1 is expressed across all major life stages and is essential, as conditional depletion of DDI1 protein in P. berghei and P. falciparum drastically reduced the asexual stage parasite development. Infection of mice with DDI1 knock-down P. berghei parasites was self-limiting and protected from the subsequent infection with both homologous and heterologous parasites, indicating potential of DDI1 knock-down parasites as a whole organism vaccine. P. falciparum DDI1 (PfDDI1) is associated with chromatin and DNA-protein crosslinks, and PfDDI1 knock-down parasites showed increased DNA-protein crosslinks and susceptibility to DNA damaging chemicals, indicating an important role for DDI1 in repair of DNA-protein crosslinks. The knock-down of PfDDI1 increased susceptibility to retroviral protease inhibitors, epoxomicin and artemisinin, which suggests that simultaneous inhibition of DDI1 could potentiate antimalarial activity of these inhibitors or drugs. Hence, the essentiality, ability of DDI1 knock-down parasites to confer protective immunity and increased susceptibility to inhibitors support Plasmodium DDI1 as a dual-target therapeutic candidate.

scholarly journals Stage-dependent effect of deferoxamine on growth of Plasmodium falciparum in vitro

Blood ◽  
1990 ◽  
Vol 76 (6) ◽  
pp. 1250-1255 ◽  
Author(s):  
S Whitehead ◽  
TE Peto
Keyword(s):  
Plasmodium Falciparum ◽  
Growth Inhibition ◽  
Antimalarial Activity ◽  
Clinical Malaria ◽  
Inhibitory Effect ◽  
Parasite Development ◽  
And Control ◽  
Speed Of Onset

Abstract Deferoxamine (DF) has antimalarial activity that can be demonstrated in vitro and in vivo. This study is designed to examine the speed of onset and stage dependency of growth inhibition by DF and to determine whether its antimalarial activity is cytostatic or cytocidal. Growth inhibition was assessed by suppression of hypoxanthine incorporation and differences in morphologic appearance between treated and control parasites. Using synchronized in vitro cultures of Plasmodium falciparum, growth inhibition by DF was detected within a single parasite cycle. Ring and nonpigmented trophozoite stages were sensitive to the inhibitory effect of DF but cytostatic antimalarial activity was suggested by evidence of parasite recovery in later cycles. However, profound growth inhibition, with no evidence of subsequent recovery, occurred when pigmented trophozoites and early schizonts were exposed to DF. At this stage in parasite development, the activity of DF was cytocidal and furthermore, the critical period of exposure may be as short as 6 hours. These observations suggest that iron chelators may have a role in the treatment of clinical malaria.

scholarly journals Antimalarial Activity of the Myxobacterial Macrolide Chlorotonil A

2014 ◽  
Vol 58 (11) ◽  
pp. 6378-6384 ◽  
Author(s):  
Jana Held ◽  
Tamirat Gebru ◽  
Markus Kalesse ◽  
Rolf Jansen ◽  
Klaus Gerth ◽  
...  
Keyword(s):  
Screening Program ◽  
Antimalarial Activity ◽  
Stage Iv ◽  
Short Exposure ◽  
Parasite Development ◽  
Content Type ◽  
Highly Active ◽  
New Antibiotics ◽  
Further Development ◽  
Antimalarial Action

ABSTRACTMyxobacteria are Gram-negative soil-dwelling bacteria belonging to the phylumProteobacteria. They are a rich source of promising compounds for clinical application, such as epothilones for cancer therapy and several new antibiotics. In the course of a bioactivity screening program of secondary metabolites produced bySorangium cellulosumstrains, the macrolide chlorotonil A was found to exhibit promising antimalarial activity. Subsequently, we evaluated chlorotonil A againstPlasmodium falciparumlaboratory strains and clinical isolates from Gabon. Chlorotonil A was highly active, with a 50% inhibitory concentration between 4 and 32 nM; additionally, no correlations between the activities of chlorotonil A and artesunate (rho, 0.208) or chloroquine (rho, −0.046) were observed.Per ostreatment ofPlasmodium berghei-infected mice with four doses of as little as 36 mg of chlorotonil A per kg of body weight led to the suppression of parasitemia with no obvious signs of toxicity. Chlorotonil A acts against all stages of intraerythrocytic parasite development, including ring-stage parasites and stage IV to V gametocytes, and it requires only a very short exposure to the parasite to exert its antimalarial action. Conclusively, chlorotonil A has an exceptional and unprecedented profile of action and represents an urgently required novel antimalarial chemical scaffold. Therefore, we propose it as a lead structure for further development as an antimalarial chemotherapeutic.

scholarly journals The Role of N6-Methyladenosine (m6A) Methylation Modifications in Hematological Malignancies

Cancers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 332
Author(s):  
Yan Zhao ◽  
Hongling Peng
Keyword(s):  
Bone Marrow ◽  
Pluripotent Stem Cells ◽  
Rna Splicing ◽  
Messenger Rna ◽  
Hematologic Malignancies ◽  
Cellular Processes ◽  
Proliferation And Differentiation ◽  
Regulatory Functions ◽  
Increased Susceptibility

Epigenetics is identified as the study of heritable modifications in gene expression and regulation that do not involve DNA sequence alterations, such as DNA methylation, histone modifications, etc. Importantly, N6-methyladenosine (m6A) methylation modification is one of the most common epigenetic modifications of eukaryotic messenger RNA (mRNA), which plays a key role in various cellular processes. It can not only mediate various RNA metabolic processes such as RNA splicing, translation, and decay under the catalytic regulation of related enzymes but can also affect the normal development of bone marrow hematopoiesis by regulating the self-renewal, proliferation, and differentiation of pluripotent stem cells in the hematopoietic microenvironment of bone marrow. In recent years, numerous studies have demonstrated that m6A methylation modifications play an important role in the development and progression of hematologic malignancies (e.g., leukemia, lymphoma, myelodysplastic syndromes [MDS], multiple myeloma [MM], etc.). Targeting the inhibition of m6A-associated factors can contribute to increased susceptibility of patients with hematologic malignancies to therapeutic agents. Therefore, this review elaborates on the biological characteristics and normal hematopoietic regulatory functions of m6A methylation modifications and their role in the pathogenesis of hematologic malignancies.

scholarly journals Role of Glutathione in Cancer Progression and Chemoresistance

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Nicola Traverso ◽  
Roberta Ricciarelli ◽  
Mariapaola Nitti ◽  
Barbara Marengo ◽  
Anna Lisa Furfaro ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Differentiation ◽  
Cancer Progression ◽  
Anticancer Agents ◽  
Cytotoxic Effects ◽  
Cellular Processes ◽  
Proliferation And Apoptosis ◽  
Glutathione Disulphide ◽  
Increased Susceptibility

Glutathione (GSH) plays an important role in a multitude of cellular processes, including cell differentiation, proliferation, and apoptosis, and disturbances in GSH homeostasis are involved in the etiology and progression of many human diseases including cancer. While GSH deficiency, or a decrease in the GSH/glutathione disulphide (GSSG) ratio, leads to an increased susceptibility to oxidative stress implicated in the progression of cancer, elevated GSH levels increase the antioxidant capacity and the resistance to oxidative stress as observed in many cancer cells. The present review highlights the role of GSH and related cytoprotective effects in the susceptibility to carcinogenesis and in the sensitivity of tumors to the cytotoxic effects of anticancer agents.

scholarly journals Human Miro Proteins Act as NTP Hydrolases through a Novel, Non-Canonical Catalytic Mechanism

2018 ◽  
Vol 19 (12) ◽  
pp. 3839 ◽  
Author(s):  
Daniel Peters ◽  
Laura Kay ◽  
Jeyanthy Eswaran ◽  
Jeremy Lakey ◽  
Meera Soundararajan
Keyword(s):  
Catalytic Mechanism ◽  
Catalytic Domain ◽  
Domain Architecture ◽  
Subcellular Localisation ◽  
Cellular Processes ◽  
Calcium Sensing ◽  
And Function ◽  
Arginine Finger ◽  
Catalytic Functions ◽  
Unique Domain

Mitochondria are highly dynamic organelles that play a central role in multiple cellular processes, including energy metabolism, calcium homeostasis and apoptosis. Miro proteins (Miros) are “atypical” Ras superfamily GTPases that display unique domain architecture and subcellular localisation regulating mitochondrial transport, autophagy and calcium sensing. Here, we present systematic catalytic domain characterisation and structural analyses of human Miros. Despite lacking key conserved catalytic residues (equivalent to Ras Y32, T35, G60 and Q61), the Miro N-terminal GTPase domains display GTPase activity. Surprisingly, the C-terminal GTPase domains previously assumed to be “relic” domains were also active. Moreover, Miros show substrate promiscuity and function as NTPases. Molecular docking and structural analyses of Miros revealed unusual features in the Switch I and II regions, facilitating promiscuous substrate binding and suggesting the usage of a novel hydrolytic mechanism. The key substitution in position 13 in the Miros leads us to suggest the existence of an “internal arginine finger”, allowing an unusual catalytic mechanism that does not require GAP protein. Together, the data presented here indicate novel catalytic functions of human Miro atypical GTPases through altered catalytic mechanisms.

scholarly journals Quantification of labile heme in live malaria parasites using a genetically encoded biosensor

2017 ◽  
Vol 114 (11) ◽  
pp. E2068-E2076 ◽  
Author(s):  
James R. Abshire ◽  
Christopher J. Rowlands ◽  
Suresh M. Ganesan ◽  
Peter T. C. So ◽  
Jacquin C. Niles
Keyword(s):  
Blood Cells ◽  
Antimalarial Activity ◽  
Cellular Damage ◽  
Malarial Parasite ◽  
Redox Activity ◽  
Parasite Development ◽  
Heme Binding ◽  
Environmental Perturbations ◽  
Hemoglobin Degradation ◽  
Relevant Component

Heme is ubiquitous, yet relatively little is known about the maintenance of labile pools of this cofactor, which likely ensures its timely bioavailability for proper cellular function. Quantitative analysis of labile heme is of fundamental importance to understanding how nature preserves access to the diverse chemistry heme enables, while minimizing cellular damage caused by its redox activity. Here, we have developed and characterized a protein-based sensor that undergoes fluorescence quenching upon heme binding. By genetically encoding this sensor in the human malarial parasite, Plasmodium falciparum, we have quantified cytosolic labile heme levels in intact, blood-stage parasites. Our findings indicate that a labile heme pool (∼1.6 µM) is stably maintained throughout parasite development within red blood cells, even during a period coincident with extensive hemoglobin degradation by the parasite. We also find that the heme-binding antimalarial drug chloroquine specifically increases labile cytosolic heme, indicative of dysregulation of this homeostatic pool that may be a relevant component of the antimalarial activity of this compound class. We propose that use of this technology under various environmental perturbations in P. falciparum can yield quantitative insights into fundamental heme biology.

scholarly journals Disassembly activity of actin-depolymerizing factor (ADF) is associated with distinct cellular processes in apicomplexan parasites

2015 ◽  
Vol 26 (17) ◽  
pp. 3001-3012 ◽  
Author(s):  
Silvia Haase ◽  
Dennis Zimmermann ◽  
Maya A. Olshina ◽  
Mark Wilkinson ◽  
Fabio Fisher ◽  
...  
Keyword(s):  
Parasite Development ◽  
Actin Depolymerizing Factor ◽  
Phenotypic Effect ◽  
Basic Residue ◽  
Human Malaria Parasite ◽  
Apicomplexan Parasites ◽  
Functional Conservation ◽  
Cellular Processes ◽  
Organelle Segregation ◽  
Biochemical Analyses

Proteins of the actin-depolymerizing factor (ADF)/cofilin family have been shown to be crucial for the motility and survival of apicomplexan parasites. However, the mechanisms by which ADF proteins fulfill their function remain poorly understood. In this study, we investigate the comparative activities of ADF proteins from Toxoplasma gondii and Plasmodium falciparum, the human malaria parasite, using a conditional T. gondii ADF-knockout line complemented with ADF variants from either species. We show that P. falciparum ADF1 can fully restore native TgADF activity, demonstrating functional conservation between parasites. Strikingly, mutation of a key basic residue (Lys-72), previously implicated in disassembly in PfADF1, had no detectable phenotypic effect on parasite growth, motility, or development. In contrast, organelle segregation was severely impaired when complementing with a TgADF mutant lacking the corresponding residue (Lys-68). Biochemical analyses of each ADF protein confirmed the reduced ability of lysine mutants to mediate actin depolymerization via filament disassembly although not severing, in contrast to previous reports. These data suggest that actin filament disassembly is essential for apicomplexan parasite development but not for motility, as well as pointing to genus-specific coevolution between ADF proteins and their native actin.

scholarly journals Chemical Target Validation Studies of Aminopeptidase in Malaria Parasites Using α-Aminoalkylphosphonate and Phosphonopeptide Inhibitors

2008 ◽  
Vol 52 (9) ◽  
pp. 3221-3228 ◽  
Author(s):  
Eithne Cunningham ◽  
Marcin Drag ◽  
Pawel Kafarski ◽  
Angus Bell
Keyword(s):  
Amino Acids ◽  
Drug Targets ◽  
Antimalarial Activity ◽  
Malarial Parasite ◽  
Parasite Development ◽  
Aminopeptidase Activity ◽  
Gene Products ◽  
Sequence Motifs ◽  
Small Peptides ◽  
Terminal Amino

ABSTRACT During its intraerythrocytic phase, the most lethal human malarial parasite, Plasmodium falciparum, digests host cell hemoglobin as a source of some of the amino acids required for its own protein synthesis. A number of parasite endopeptidases (including plasmepsins and falcipains) process the globin into small peptides. These peptides appear to be further digested to free amino acids by aminopeptidases, enzymes that catalyze the sequential cleavage of N-terminal amino acids from peptides. Aminopeptidases are classified into different evolutionary families according to their sequence motifs and preferred substrates. The aminopeptidase inhibitor bestatin can disrupt parasite development, suggesting that this group of enzymes might be a chemotherapeutic target. Two bestatin-susceptible aminopeptidase activities, associated with gene products belonging to the M1 and M17 families, have been described in blood-stage P. falciparum parasites, but it is not known whether one or both are required for parasite development. To establish whether inhibition of the M17 aminopeptidase is sufficient to confer antimalarial activity, we evaluated 35 aminoalkylphosphonate and phosphonopeptide compounds designed to be specific inhibitors of M17 aminopeptidases. The compounds had a range of activities against cultured P. falciparum parasites with 50% inhibitory concentrations down to 14 μM. Some of the compounds were also potent inhibitors of parasite aminopeptidase activity, though it appeared that many were capable of inhibiting the M1 as well as the M17 enzyme. There was a strong correlation between the potencies of the compounds against whole parasites and against the enzyme, suggesting that M17 and/or M1 aminopeptidases may be valid antimalarial drug targets.

Brr2p RNA helicase with a split personality: insights into structure and function

2010 ◽  
Vol 38 (4) ◽  
pp. 1105-1109 ◽  
Author(s):  
Daniela Hahn ◽  
Jean D. Beggs
Keyword(s):  
Domain Architecture ◽  
Rna Helicase ◽  
Structure And Function ◽  
Mrna Splicing ◽  
Eye Disease ◽  
Rna Helicases ◽  
Cellular Processes ◽  
Biochemical Studies ◽  
Split Personality ◽  
And Function

RNA helicases are involved in many cellular processes. Pre-mRNA splicing requires eight different DExD/H-box RNA helicases, which facilitate spliceosome assembly and remodelling of the intricate network of RNA rearrangements that are central to the splicing process. Brr2p, one of the spliceosomal RNA helicases, stands out through its unusual domain architecture. In the present review we highlight the advances made by recent structural and biochemical studies that have important implications for the mechanism and regulation of Brr2p activity. We also discuss the involvement of human Brr2 in retinitis pigmentosa, a degenerative eye disease, and how its functions in splicing might connect to the molecular pathology of the disease.

scholarly journals Retargeting azithromycin analogues to have dual-modality antimalarial activity

BMC Biology ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Amy L. Burns ◽  
Brad E. Sleebs ◽  
Ghizal Siddiqui ◽  
Amanda E. De Paoli ◽  
Dovile Anderson ◽  
...  
Keyword(s):  
Plasmodium Knowlesi ◽  
Antimalarial Activity ◽  
Treatment Strategies ◽  
Food Vacuole ◽  
Parasite Development ◽  
Malaria Parasites ◽  
Killing Activity ◽  
Delayed Death ◽  
Artemisinin Combination Therapies

Abstract Background Resistance to front-line antimalarials (artemisinin combination therapies) is spreading, and development of new drug treatment strategies to rapidly kill Plasmodium spp. malaria parasites is urgently needed. Azithromycin is a clinically used macrolide antibiotic proposed as a partner drug for combination therapy in malaria, which has also been tested as monotherapy. However, its slow-killing ‘delayed-death’ activity against the parasite’s apicoplast organelle and suboptimal activity as monotherapy limit its application as a potential malaria treatment. Here, we explore a panel of azithromycin analogues and demonstrate that chemical modifications can be used to greatly improve the speed and potency of antimalarial action. Results Investigation of 84 azithromycin analogues revealed nanomolar quick-killing potency directed against the very earliest stage of parasite development within red blood cells. Indeed, the best analogue exhibited 1600-fold higher potency than azithromycin with less than 48 hrs treatment in vitro. Analogues were effective against zoonotic Plasmodium knowlesi malaria parasites and against both multi-drug and artemisinin-resistant Plasmodium falciparum lines. Metabolomic profiles of azithromycin analogue-treated parasites suggested activity in the parasite food vacuole and mitochondria were disrupted. Moreover, unlike the food vacuole-targeting drug chloroquine, azithromycin and analogues were active across blood-stage development, including merozoite invasion, suggesting that these macrolides have a multi-factorial mechanism of quick-killing activity. The positioning of functional groups added to azithromycin and its quick-killing analogues altered their activity against bacterial-like ribosomes but had minimal change on ‘quick-killing’ activity. Apicoplast minus parasites remained susceptible to both azithromycin and its analogues, further demonstrating that quick-killing is independent of apicoplast-targeting, delayed-death activity. Conclusion We show that azithromycin and analogues can rapidly kill malaria parasite asexual blood stages via a fast action mechanism. Development of azithromycin and analogues as antimalarials offers the possibility of targeting parasites through both a quick-killing and delayed-death mechanism of action in a single, multifactorial chemotype.

Sign in / Sign up

Export Citation Format

Share Document