1. A photosynthetic alveolate closely related to apicomplexan parasites.
- Author
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Moore RB, Oborník M, Janouskovec J, Chrudimský T, Vancová M, Green DH, Wright SW, Davies NW, Bolch CJ, Heimann K, Slapeta J, Hoegh-Guldberg O, Logsdon JM, and Carter DA
- Subjects
- Animals, Cell Nucleus genetics, Chlorophyll metabolism, Chlorophyll A, Codon genetics, Eukaryotic Cells cytology, Eukaryotic Cells ultrastructure, Parasites genetics, Parasites ultrastructure, Plasmodium falciparum classification, Plastids genetics, RNA, Ribosomal genetics, Eukaryotic Cells classification, Eukaryotic Cells metabolism, Parasites classification, Parasites cytology, Photosynthesis, Phylogeny, Plastids metabolism
- Abstract
Many parasitic Apicomplexa, such as Plasmodium falciparum, contain an unpigmented chloroplast remnant termed the apicoplast, which is a target for malaria treatment. However, no close relative of apicomplexans with a functional photosynthetic plastid has yet been described. Here we describe a newly cultured organism that has ultrastructural features typical for alveolates, is phylogenetically related to apicomplexans, and contains a photosynthetic plastid. The plastid is surrounded by four membranes, is pigmented by chlorophyll a, and uses the codon UGA to encode tryptophan in the psbA gene. This genetic feature has been found only in coccidian apicoplasts and various mitochondria. The UGA-Trp codon and phylogenies of plastid and nuclear ribosomal RNA genes indicate that the organism is the closest known photosynthetic relative to apicomplexan parasites and that its plastid shares an origin with the apicoplasts. The discovery of this organism provides a powerful model with which to study the evolution of parasitism in Apicomplexa.
- Published
- 2008
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