The malaria parasite is a plague of humanity. Understanding its biology and blocking essential parasite biochemical pathways are ways of controlling and possibly defeating malaria. During its complex life cycle, the parasite undergoes cycles of asexual replication in erythrocytes, then egresses from them to invade fresh erythrocytes. An essential cascade involved in egress, which includes at least two enzymes, has recently been discovered in P. Jalciparum . The parasite cGMP-dependent kinase PKG triggers the discharge of a serine protease called SUBl from secretory organelles called exonemes and its subsequent activation. SUBl cleaves several parasite substrates, enabling egress and preparing the merozoites for invasion. Blocking either enzyme inhibits egress, making them potential antimalarial targets. Whilst the most dangerous cause of human malaria is Plasmodium Jalciparum, the zoonotic species P. knowlesi can also cause severe disease and death. P. knowlesi has recently been adapted to in vitro culture in human erythrocytes, providing an excellent tool to study this human pathogen in depth. Shedding light on the specificity and regulation of P. knowlesi PKG and SUBl will provide information about an important biochemical pathwaywhich may be conserved across human Pla'smod~um species. In this study, P. knowlesi PKG was characterized using selective inhibitors of the enzyme that block egress of P. knowlesi parasites in vitro.PkSUB 1 was expressed in a recombinant enzymatically active form and new selective inhibitors of PfSUBl and PkSUBl were designed using a combination of in silico,in vitro and substrate based approaches. Some of these compounds were shown to inhibit both egress and SUB1-mediated processing of endogenous parasite substrates. The results show that the essential role of PKG and SUBl in egress is conserved in P .
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:664284 |
| Date | January 2014 |
| Creators | Penzo, Maria |
| Publisher | Open University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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