Over the last decade, research on the most studied parasite, Plasmodium falciparum, has disclosed significant findings in protease research. Detailed descriptions of the individual roles of protease isoenzymes from various protease classes encoded by the parasite genome have been elucidated, along with their functional and biochemical characterizations. These insights have enabled the development of innovative chemotherapy using low molecular weight inhibitors targeting specific molecular sites. Progress has been made in understanding the proteolytic cascade associated with the apical complex, particularly the roles of aspartyl proteases plasmepsins IX and X as master regulators. Additionally, advancements in direct and alternative methods of proteasome inhibition and expression regulation have been achieved. Research on digestive/food vacuole-associated proteases, with a focus on essential metalloproteases, has also seen significant developments. The rise of extensive genomic datasets and functional genomic tools for other parasitic organisms now allows these approaches to be applied to the study and treatment of other, less known parasitic diseases, aiming to uncover specific biological mechanisms and develop innovative, less toxic chemotherapies.
- MeSH
- antimalarika * farmakologie terapeutické užití MeSH
- inhibitory proteas * terapeutické užití MeSH
- lidé MeSH
- malárie farmakoterapie MeSH
- Plasmodium falciparum * enzymologie účinky léků genetika MeSH
- proteasy metabolismus genetika MeSH
- tropická malárie farmakoterapie parazitologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
The Propagation of Plasmodium spp. and Babesia/Theileria spp. vertebrate blood stages relies on the mediated acquisition of nutrients available within the host's red blood cell (RBC). The cellular processes of uptake, trafficking and metabolic processing of host RBC proteins are thus crucial for the intraerythrocytic development of these parasites. In contrast to malarial Plasmodia, the molecular mechanisms of uptake and processing of the major RBC cytoplasmic protein hemoglobin remain widely unexplored in intraerythrocytic Babesia/Theileria species. In the paper, we thus provide an updated comparison of the intraerythrocytic stage feeding mechanisms of these two distantly related groups of parasitic Apicomplexa. As the associated metabolic pathways including proteolytic degradation and networks facilitating heme homeostasis represent attractive targets for diverse antimalarials, and alterations in these pathways underpin several mechanisms of malaria drug resistance, our ambition is to highlight some fundamental differences resulting in different implications for parasite management with the potential for novel interventions against Babesia/Theileria infections.
- Publikační typ
- časopisecké články MeSH
Therapeutic agents with novel mechanisms of action are urgently needed to counter the emergence of drug-resistant infections. Several decades of research into proteases of disease agents have revealed enzymes well suited for target-based drug development. Among them are the three recently validated proteolytic targets: proteasomes of the malarial parasite Plasmodium falciparum, aspartyl proteases of P. falciparum (plasmepsins) and the Sars-CoV-2 viral proteases. Despite some unfulfilled expectations over previous decades, the three reviewed targets clearly demonstrate that selective protease inhibitors provide effective therapeutic solutions for the two most impacting infectious diseases nowadays-malaria and COVID-19.
- MeSH
- aspartátové endopeptidasy metabolismus MeSH
- COVID-19 enzymologie metabolismus MeSH
- farmakoterapie COVID-19 MeSH
- inhibitory proteas farmakologie MeSH
- lidé MeSH
- malárie farmakoterapie enzymologie metabolismus MeSH
- Plasmodium falciparum účinky léků patogenita MeSH
- proteasomový endopeptidasový komplex účinky léků MeSH
- SARS-CoV-2 účinky léků patogenita MeSH
- vyvíjení léků metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Host blood proteins, represented mainly by hemoglobin and serum albumin, serve as the ultimate source of amino acids needed for de novo protein synthesis during tick development and reproduction. While uptake and processing of hemoglobin by tick gut cells have been studied in detail, molecular mechanisms of host serum albumin degradation remain unknown. In this work, we have used artificial membrane feeding of Ixodes ricinus females on a hemoglobin-free diet in order to characterize the proteolytic machinery involved in albuminolysis. Morphological comparisons of ticks fed on whole blood (BF) and serum (SF) at microscopic and ultrastructural levels showed that albumin and hemoglobin have different trafficking routes in tick gut cells. Analysis in vitro with selective inhibitors demonstrated that albumin is degraded at an acidic pH by a network of cysteine and aspartic peptidases with predominant involvement of cysteine cathepsins having endo- and exopeptidase activities. The cleavage map of albumin and the roles of individual peptidases in albumin degradation were determined. These results indicate that the albuminolytic pathway is controlled by the same proteolytic system that is responsible for hemoglobinolysis. This was further supported by the overall similarity of gut peptidase profiles in SF and BF ticks at the transcriptional and enzymatic activity levels. In conclusion, our work provides evidence that although hemoglobin and albumin are transported differentially during heterophagy they are digested by a common multienzyme proteolytic network. This central digestive system, critical for successful blood feeding in tick females, thus represents a valuable target for novel anti-tick interventions.
- MeSH
- aspartátové proteasy metabolismus MeSH
- cysteinové proteasy metabolismus MeSH
- hemoglobiny metabolismus MeSH
- klíště enzymologie MeSH
- koncentrace vodíkových iontů MeSH
- proteolýza * MeSH
- sérový albumin metabolismus MeSH
- stanovení celkové genové exprese MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Inhibition of aspartic cathepsin D-like peptidases (APDs) has been often discussed as an antiparasite intervention strategy. APDs have been considered as virulence factors of Trypanosoma cruzi and Leishmania spp., and have been demonstrated to have important roles in protein trafficking mechanisms of apicomplexan parasites. APDs also initiate blood digestion as components of multienzyme proteolytic complexes in malaria, platyhelminths, nematodes, and ticks. Increasing DNA and RNA sequencing data indicate that parasites express multiple APD isoenzymes of various functions that can now be specifically evaluated using new functional-genomic and biochemical tools, from which we can further assess the potential of APDs as targets for novel effective intervention strategies against parasitic diseases that still pose an alarming threat to mankind.
- MeSH
- antiparazitární látky farmakologie terapeutické užití MeSH
- inhibitory enzymů farmakologie MeSH
- lékové transportní systémy * MeSH
- parazitární nemoci farmakoterapie enzymologie MeSH
- paraziti enzymologie MeSH
- proteasy metabolismus MeSH
- transport proteinů genetika MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Blood-protein digestion is a key physiological process providing essential nutrients for ticks and is a prerequisite for the transmission of tick-borne pathogens. Recently, substantial progress has been made in determining the proteolytic machinery in tick gut tissue, which is based on a dynamic multienzyme network capable of processing a vast amount of host blood. In this article we summarize our current knowledge of the molecular mechanisms of tick hematophagy and their similarities to those of Platyhelminthes, nematodes, and Plasmodium. Future research perspectives, including the potential for rational control of ticks and transmitted diseases, are also discussed.
- MeSH
- gastrointestinální trakt enzymologie MeSH
- klíšťata fyziologie MeSH
- krevní proteiny metabolismus MeSH
- trávení fyziologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
To identify the gut-associated tick aspartic hemoglobinase, this work focuses on the functional diversity of multiple Ixodes ricinus cathepsin D forms (IrCDs). Out of three encoding genes representing Ixodes scapularis genome paralogs, IrCD1 is the most distinct enzyme with a shortened propeptide region and a unique pattern of predicted post-translational modifications. IrCD1 gene transcription is induced by tick feeding and is restricted to the gut tissue. The hemoglobinolytic role of IrCD1 was further supported by immunolocalization of IrCD1 in the vesicles of tick gut cells. Properties of recombinantly expressed rIrCD1 are consistent with the endo-lysosomal environment because the zymogen is autoactivated and remains optimally active in acidic conditions. Hemoglobin cleavage pattern of rIrCD1 is identical to that produced by the native enzyme. The preference for hydrophobic residues at the P1 and P1' position was confirmed by screening a novel synthetic tetradecapeptidyl substrate library. Outside the S1-S1' regions, rIrCD1 tolerates most amino acids but displays a preference for tyrosine at P3 and alanine at P2'. Further analysis of the cleavage site location within the peptide substrate indicated that IrCD1 is a true endopeptidase. The role in hemoglobinolysis was verified with RNAi knockdown of IrCD1 that decreased gut extract cathepsin D activity by >90%. IrCD1 was newly characterized as a unique hemoglobinolytic cathepsin D contributing to the complex intestinal proteolytic network of mainly cysteine peptidases in ticks.
- MeSH
- genetická transkripce fyziologie MeSH
- genom fyziologie MeSH
- hemoglobiny genetika metabolismus MeSH
- kathepsin D genetika metabolismus MeSH
- klíště enzymologie genetika MeSH
- posttranslační úpravy proteinů fyziologie MeSH
- proteiny členovců genetika metabolismus MeSH
- rekombinantní proteiny genetika metabolismus MeSH
- střeva enzymologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Cysteine proteases have been discovered in various bloodfeeding ectoparasites. Here, we assemble the available information about the function of these peptidases and reveal their role in hematophagy and parasite development. While most of the data shed light on key proteolytic events that play a role in arthropod physiology, we also report on the association of cysteine proteases with arthropod vectorial capacity. With emphasis on ticks, specifically Ixodes ricinus, we finally propose a model about the contribution of cysteine peptidases to blood digestion and how their concerted action with other tick midgut proteases leads to the absorbance of nutrients by the midgut epithelial cells.
- MeSH
- členovci enzymologie MeSH
- Culicidae enzymologie MeSH
- cysteinové proteasy metabolismus MeSH
- klíšťata enzymologie MeSH
- paraziti enzymologie MeSH
- stravovací zvyklosti fyziologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
