Related Experiment Videos
Developmental modulation of protein synthetic patterns by the human malarial parasite Plasmodium falciparum
Abstract:
Under conditions of in vitro culture, Plasmodium falciparum incorporated amino acids into particulate (membrane) and soluble proteins in a pattern which changed sequentially and which was dependent upon the stage of parasite maturation. Synchronized cultures pulse labeled with a mixture of 15 14C-labeled amino acids or [14C]histidine alone displayed stage-related patterns of polypeptide biosynthesis. Certain plasmodial proteins were associated with both particulate (membrane) and soluble fractions, whereas others appeared to be specific to a given fraction. Proteolysis of intact infected cells with pronase under conditions which removed 97 +/- 2.2% of the endogenous red cell acetylcholinesterase activity did not cause the apparent removal of any radiolabeled proteins; this suggests the absence of externally exposed, parasite-synthesized proteins in the infected red cell membrane. Such a result was consistent whether the radiolabel was [14C]histidine or the 14C-labeled amino acid mixture. These results indicate that specific modulation of parasite biosynthetic patterns occurs during the asexual reproductive cycle and is probably one mechanism whereby parasite differentiation occurs. Despite the formation of surface excrescences on infected red cells containing mature parasites, results of surface digestion experiments failed to demonstrate the presence of surface-exposed plasmodial proteins.
Insights
Plasmodium falciparum synthesizes stage-specific proteins during its maturation cycle. These parasite proteins are not exposed on the surface of infected red blood cells, even with visible surface changes.
Area of Science:
- Molecular parasitology
- Cell biology
- Biochemistry
Background:
- Plasmodium falciparum, the causative agent of malaria, undergoes complex developmental stages within red blood cells.
- Understanding parasite protein synthesis and localization is crucial for developing effective interventions.
Purpose of the Study:
- To investigate the stage-dependent patterns of protein biosynthesis in Plasmodium falciparum.
- To determine the localization of parasite-synthesized proteins, particularly in the infected red blood cell membrane.
Main Methods:
- In vitro culture of synchronized Plasmodium falciparum.
- Pulse-labeling with 14C-labeled amino acids and [14C]histidine.
- Fractionation of parasite proteins into particulate (membrane) and soluble components.
- Proteolysis of infected red blood cells with pronase to assess surface protein exposure.
Main Results:
- Plasmodium falciparum incorporated amino acids into proteins in a stage-specific manner during its maturation.
- Some parasite proteins were found in both membrane and soluble fractions, while others were fraction-specific.
- Pronase digestion of infected red blood cells did not remove any radiolabeled parasite proteins, indicating no externally exposed parasite proteins.
Conclusions:
- Parasite protein biosynthesis is modulated during the asexual reproductive cycle, suggesting a mechanism for parasite differentiation.
- Despite surface alterations on infected red blood cells, parasite-synthesized proteins are not exposed on the external surface.