TY - JOUR A1 - von Bohl, Andreas A1 - Kuehn, Andrea A1 - Simon, Nina A1 - Nkwouano Ngongang, Vanesa A1 - Spehr, Marc A1 - Baumeister, Stefan A1 - Przyborski, Jude M. A1 - Fischer, Rainer A1 - Pradel, Gabriele T1 - A WD40-repeat protein unique to malaria parasites associates with adhesion protein complexes and is crucial for blood stage progeny JF - Malaria Journal N2 - 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. KW - PfCCp protein KW - Pfs230 KW - PfAMA1 KW - WD40 KW - gametocyte KW - microneme KW - merozoite KW - plasmodium falciparum KW - malaria Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-139728 VL - 14 IS - 435 ER - TY - JOUR A1 - Ngwa, Che Julius A1 - Scheuermayer, Matthias A1 - Mair, Gunnar Rudolf A1 - Kern, Selina A1 - Brügl, Thomas A1 - Wirth, Christine Clara A1 - Aminake, Makoah Nigel A1 - Wiesner, Jochen A1 - Fischer, Rainer A1 - Vilcinskas, Andreas A1 - Pradel, Gabriele T1 - Changes in the transcriptome of the malaria parasite Plasmodium falciparum during the initial phase of transmission from the human to the mosquito JF - BMC Genomics N2 - Background: The transmission of the malaria parasite Plasmodium falciparum from the human to the mosquito is mediated by dormant sexual precursor cells, the gametocytes, which become activated in the mosquito midgut. Because gametocytes are the only parasite stages able to establish an infection in the mosquito, they play a crucial role in spreading the tropical disease. The human-to-mosquito transmission triggers important molecular changes in the gametocytes, which initiate gametogenesis and prepare the parasite for life-cycle progression in the insect vector. Results: To better understand gene regulations during the initial phase of malaria parasite transmission, we focused on the transcriptome changes that occur within the first half hour of parasite development in the mosquito. Comparison of mRNA levels of P. falciparum gametocytes before and 30 min following activation using suppression subtractive hybridization (SSH) identified 126 genes, which changed in expression during gametogenesis. Among these, 17.5% had putative functions in signaling, 14.3% were assigned to cell cycle and gene expression, 8.7% were linked to the cytoskeleton or inner membrane complex, 7.9% were involved in proteostasis and 6.4% in metabolism, 12.7% were cell surface-associated proteins, 11.9% were assigned to other functions, and 20.6% represented genes of unknown function. For 40% of the identified genes there has as yet not been any protein evidence. For a subset of 27 genes, transcript changes during gametogenesis were studied in detail by real-time RT-PCR. Of these, 22 genes were expressed in gametocytes, and for 15 genes transcript expression in gametocytes was increased compared to asexual blood stage parasites. Transcript levels of seven genes were particularly high in activated gametocytes, pointing at functions downstream of gametocyte transmission to the mosquito. For selected genes, a regulated expression during gametogenesis was confirmed on the protein level, using quantitative confocal microscopy. Conclusions: The obtained transcriptome data demonstrate the regulations of gene expression immediately following malaria parasite transmission to the mosquito. Our findings support the identification of proteins important for sexual reproduction and further development of the mosquito midgut stages and provide insights into the genetic basis of the rapid adaption of Plasmodium to the insect vector. KW - parasitophorous vacuole KW - sexual development KW - gametocyte KW - transcriptome KW - signal peptide peptidase KW - host cell interface KW - alpha-tubulin-II KW - life-cycle KW - protein kinases KW - in-vitro KW - erythroyte invation KW - blocking antibodies KW - malaria KW - plasmodium falciparum KW - gametogenesis KW - mosquito KW - transmission Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-121905 SN - 1471-2164 VL - 14 IS - 256 ER - TY - JOUR A1 - Makoah Nigel, Animake A1 - Arndt, Hans-Dieter A1 - Pradel, Gabriele T1 - The proteasome of malaria parasites: A multi-stage drug target for chemotherapeutic intervention? JF - International Journal for Parasitology: Drugs and Drug Resistance N2 - The ubiquitin/proteasome system serves as a regulated protein degradation pathway in eukaryotes, and is involved in many cellular processes featuring high protein turnover rates, such as cell cycle control, stress response and signal transduction. In malaria parasites, protein quality control is potentially important because of the high replication rate and the rapid transformations of the parasite during life cycle progression. The proteasome is the core of the degradation pathway, and is a major proteolytic complex responsible for the degradation and recycling of non-functional ubiquitinated proteins. Annotation of the genome for Plasmodium falciparum, the causative agent of malaria tropica, revealed proteins with similarity to human 26S proteasome subunits. In addition, a bacterial ClpQ/hslV threonine peptidase-like protein was identified. In recent years several independent studies indicated an essential function of the parasite proteasome for the liver, blood and transmission stages. In this review, we compile evidence for protein recycling in Plasmodium parasites and discuss the role of the 26S proteasome as a prospective multi-stage target for antimalarial drug discovery programs. KW - plasmodium falciparum KW - proteasome KW - ubiquitin KW - inhibitor Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-137777 VL - 2 ER -