@phdthesis{Simon2012,
  author    = {Simon, Nina Monica},
  title     = {Molecular interactions of the malaria parasite Plasmodium falciparum during the sexual reproduction in the mosquito midgut},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-72403},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2012},
  abstract  = {The sexual phase of Plasmodium falciparum begins with the differentiation of intraerythrocytic sexual stages, termed gametocytes, in the human host. Mature gametocytes circulate in the peripheral blood and are taken up by the mosquito during the blood meal. These stages are essential for the spread of the malaria disease and form gametes in the mosquito midgut within minutes. A highly conserved family of six secreted proteins has been identified in Plasmodium falciparum. They comprise multiple adhesive domains and are termed PfCCp1 through PfCCp5, and PfFNPA. It was revealed in this work that PfCCp multi-domain adhesion proteins form protein complexes in gametocytes and on the surface of newly emerged macrogametes by adhesion domain-mediated binding. Co-Immunoprecipitation assays with activated gametocyte lysates show interactions between PfCCp proteins and indicate surface association via Pfs230 and Pfs25. Pfs230 is connected with the plasma membrane of the parasite by its interaction partner Pfs48/45. This protein is linked to the plasma membrane by a GPI anchor and presumably retains the multi-protein complex on the surface of newly emerged macrogametes in the mosquito midgut. A WD40 domain containing protein was identified to be part of this protein complex. It might serve as platform for the assembly of the multi protein complex or mediate the interplay among proteins, as suggested from known functions of the WD40 domain repeats. During egress from the host erythrocyte, the emerging gametes become vulnerable to factors of the human complement, which is taken up with the blood meal. In this thesis it was found that the complement system is active for about one hour post feeding. Macrogametes defend against complement-mediated lysis by co-opting the human complement regulators Factor H and FHL-1 from the blood-meal. These serum proteins bind via its SCR domains 5-7 to the surface of macrogametes. Once bound, they trigger complement inactivation of the alternative pathway, which prevents induction of complement lysis on the surface of the malaria parasite. Antibodies against Factor H are able to impair the sexual development in vitro and are able to block transmission to the mosquito. Interaction studies on endogenous proteins and immobilized recombinant proteins revealed the PfGAP50 protein as binding partner of Factor H and FHL-1. This protein was hitherto described as a glideosome-associated protein in invasive parasite stages, but has not yet been characterized in gametes. First localization studies indicate a relocation of PfGAP50 from the inner membrane complex to the surface of macrogametes. Malaria still persists as one of the deadliest infectious diseases worldwide. Investigations on the essential transmissive stages, gametocytes and gametes of Plasmodium falciparum, stood in the background of research for a long time. This work deciphered details on protein interactions on the surface of the malaria parasite and provides first information about coactions between the parasite and the human complement in the mosquito midgut.},
  subject      = {Plasmodium falciparum},
  language  = {en}
}
@article{vonBohlKuehnSimonetal.2015,
  author    = {von Bohl, Andreas and Kuehn, Andrea and Simon, Nina and Nkwouano Ngongang, Vanesa and Spehr, Marc and Baumeister, Stefan and Przyborski, Jude M. and Fischer, Rainer and Pradel, Gabriele},
  title     = {A WD40-repeat protein unique to malaria parasites associates with adhesion protein complexes and is crucial for blood stage progeny},
  series = {Malaria Journal},
  volume    = {14},
  journal   = {Malaria Journal},
  number    = {435},
  doi       = {10.1186/s12936-015-0967-x},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-139728},
  year      = {2015},
  abstract  = {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.},
  language  = {en}
}