Comprehensive functional characterization of endosymbiotic organelles
Eukaryotes have a very complex cellular structure. These cells consist of many different chambers, so called organelles, each with their own function. The mitochondrion is one such specialized organelle, often referred to as the cell’s power plant, while in most cells it is the main site of energy production. Mitochondria originate from a so-called endosymbiotic event where the ancestral eukaryote engulfed an aerobic bacterium without completely consuming it. This explains some of the characteristics of the organelle, such as its double membrane and the presence of a small genome. While human liver and muscle cells may contain 100’s to 1000’s of mitochondria, malaria parasites only have a single and abnormal mitochondrion, which is essential for the parasite’s survival. Indeed, one of the most effective anti-malarial drugs, atovaquone, kills the parasite by targeting a mitochondrial protein. Nevertheless, the malaria parasite mitochondrion remains poorly understood. The malaria parasite has another such endosymbiotic organelle, which originates from the engulfment of a red algal cell after which only the photosynthetic plastid was retained. Due to its peculiar heritage, this four-membrane bound organelle, which has lost its photosynthetic capacity in the malaria parasite, has been generally considered another promising drug target.
(The picture shows a sporulated P. berghei oocyst with each sporozoite harbouring a single red mitochondrion and green apicoplast. Image recorded by Joachim Matz.)
Taco Kooij 