9 research outputs found
Portuguese history storyboard
This paper intends to present relevant facts about the Portuguese culture
and history, so as to enable a better understanding of who the Portuguese are
and provide an overall perspective of the course of history in this westernmost
part of Europe. Although the choice of historical facts was subjective by nature,
it is believed it achieves the aim of presenting information in a critical but
blithesome way, with a view to also deconstructing national stereotypes, such
as that Portuguese people are always late or are crazy about football. Finally, it
focuses on some information about the Portuguese language mainly to serve as
a term of comparison with other European languages
Funktionale Charakterisierung der regulativen Proteine PfWLP1 und PfGPCR1 in den Sexualstadien des Malariaerregers Plasmodium falciparum
Despite partial success in rolling back malaria, it is still one of the most abundant and deadliest diseases worldwide. The efficient fight against the tropical disease is currently endangered due to the increase in drug resistances. Therefore the identification of novel drug targets is indispensable. The WHO recommends not only to focus on the asexual blood stages, which are causing the main symptoms, but also takes the gametocytes of the intracellular parasite of the genus Plasmodium into account. These are essential for the transmission from the human host to the mosquito vector and are therefore the prime targets for transmission-blocking drugs or vaccines. Thus the aim of this thesis was to functionally characterize two candidate proteins from almost unknown protein classes in P. falciparum.The first candidate belongs to the family of WD40-proteins, which are acting as a scaffold for the assembly of multimeric protein complexes in eukaryotic cells. The findings of this thesis showed that the WD40-protein PfWLP1 (WD40-repeat protein-like protein 1) is one of the few Plasmodium-specific WD40-proteins. It is expressed in the asexual blood and sexual stages and partially co-localizes with structural elements, like microtubules, underneath the plasmamembrane. Furthermore PfWLP1 associates with the adhesion proteins PfAMA1 (apical membrane protein 1) in merozoites and Pfs230 and PfCCp1 (LCCL domain-containing protein 1) in gametocytes. Reverse genetics failed to disrupt the pfwlp1 gene locus, while HA-tagging was feasible, implying a crucial function of PfWLP1 during the intraerythrotic replication. The presented data suggest that PfWLP1 supports the stability of adhesion protein complexes during the life cycle of P. falciparum.The second candidate was PfGPCR1 (G-protein coupled receptor), which was first annotated as a putative GPCR but could be assigned to the family of eukaryotic LanCL-proteins (Lanthionin Synthetase C-like) within this thesis. Further it was shown that PfGPCR1 is exclusively expressed in female gametocytes, belonging to one of the few identified female-specific proteins in P. falciparum. The loss of PfGPCR1 by gene disruption led to a significant reduced transmission of the parasite. Furthermore in vitro protein-protein interaction studies showed that PfGPCR1 interacts with the plasmodial Akt-kinase (PfPKB), comparable to hLanCL2 in human liver cells. The results of this thesis suggest an important role of PfGPCR1 within the PfPKB-signaling pathway in female gametocytes during the transmission of the parasite from the human host to the mosquito vector.The here reported findings display the first characterization of a Plasmodium-specific WD40-potein and of the first plasmodial LanCL-protein and demonstrate the relevance of these protein classes in the life cycle of P. falciparum. Further analyses could not only unravel their unique molecular function in detail, but could also contribute to the development of new antimalarial drugs
A WD40-repeat protein unique to malaria parasites associates with adhesion protein complexes and is crucial for blood stage progeny
Background
During development in human erythrocytes, Plasmodium falciparum parasites display a remarkable number of adhesive proteins on their plasma membrane. In the invasive merozoites, these include members of the PfMSP1 and PfAMA1/RON complexes, which facilitate contact between merozoites and red blood cells. In gametocytes, sexual precursor cells mediating parasite transmission to the mosquito vector, plasma membrane-associated proteins primarily belong to the PfCCp and 6-cys families with roles in fertilization. This study describes a newly identified WD40-repeat protein unique to Plasmodium species that associates with adhesion protein complexes of both merozoites and gametocytes.
Methods
The WD40-repeat protein-like protein PfWLP1 was identified via co-immunoprecipitation assays followed by mass spectrometry and characterized using biochemical and immunohistochemistry methods. Reverse genetics were employed for functional analysis.
Results
PfWLP1 is expressed both in schizonts and gametocytes. In mature schizonts, the protein localizes underneath the merozoite micronemes and interacts with PfAMA1, while in gametocytes PfWLP1 primarily accumulates underneath the plasma membrane and associates with PfCCp1 and Pfs230. Reverse genetics failed to disrupt the pfwlp1 gene, while haemagglutinin-tagging was feasible, suggesting a crucial function for PfWLP1 during blood stage replication.
Conclusions
This is the first report on a plasmodial WD40-repeat protein associating with cell adhesion proteins. Since WD40 domains are known to mediate protein–protein contact by serving as a rigid scaffold for protein interactions, the presented data suggest that PfWLP1 supports the stability of adhesion protein complexes of the plasmodial blood stages