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The apicomplexan plastid and its evolution.

Sato S - Cell. Mol. Life Sci. (2011)

Bottom Line: Protistan species belonging to the phylum Apicomplexa have a non-photosynthetic secondary plastid-the apicoplast.Although its tiny genome and even the entire nuclear genome has been sequenced for several organisms bearing the organelle, the reason for its existence remains largely obscure.Some of the functions of the apicoplast, including housekeeping ones, are significantly different from those of other plastids, possibly due to the organelle's unique symbiotic origin.

View Article: PubMed Central - PubMed

Affiliation: Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London, UK. ssato@nimr.mrc.ac.uk

ABSTRACT
Protistan species belonging to the phylum Apicomplexa have a non-photosynthetic secondary plastid-the apicoplast. Although its tiny genome and even the entire nuclear genome has been sequenced for several organisms bearing the organelle, the reason for its existence remains largely obscure. Some of the functions of the apicoplast, including housekeeping ones, are significantly different from those of other plastids, possibly due to the organelle's unique symbiotic origin.

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Apicomplexans and the plastid. a Phylogeny of alveolates and distribution of the plastid. The phylogenetic tree was drawn based on the nuclear-encoded 18S rRNA sequences of representative species available in the databases and suggests only topological relationships between taxa. Distribution of the plastid in most Gregarinasina species has not yet been studied (see text). b Phylogeny of the plastids and their variety. Like red plastids (purple), apicoplasts (red, orange, yellow) have the genome encoding sufB, while organisms with green plastids (green) have the gene encoded in the nucleus. Unlike other plastids, the apicoplast genomes lack 5S rRNA gene (rnf). Like other plastid-bearing organisms, Toxoplasma, Eimeria, and Plasmodium have the Suf system incorporating the SufBCD complex, while Babesia and Theileria lack genes specifying the components of the complex. Toxoplasma, Eimeria, and Plasmodium have a unique hybrid-type heme pathway that involves mitochondrial ALA syntase (ALAS). Although Babesia lacks the heme pathway, it has the PBGS gene forming a tight gene cluster with the SPP gene in the nuclear genome like Toxoplasma, Eimeria, and Plasmodium. Unlike other organisms, Eimeria lacks the intron in the trnL(UAA) gene in the plastid genome
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Fig1: Apicomplexans and the plastid. a Phylogeny of alveolates and distribution of the plastid. The phylogenetic tree was drawn based on the nuclear-encoded 18S rRNA sequences of representative species available in the databases and suggests only topological relationships between taxa. Distribution of the plastid in most Gregarinasina species has not yet been studied (see text). b Phylogeny of the plastids and their variety. Like red plastids (purple), apicoplasts (red, orange, yellow) have the genome encoding sufB, while organisms with green plastids (green) have the gene encoded in the nucleus. Unlike other plastids, the apicoplast genomes lack 5S rRNA gene (rnf). Like other plastid-bearing organisms, Toxoplasma, Eimeria, and Plasmodium have the Suf system incorporating the SufBCD complex, while Babesia and Theileria lack genes specifying the components of the complex. Toxoplasma, Eimeria, and Plasmodium have a unique hybrid-type heme pathway that involves mitochondrial ALA syntase (ALAS). Although Babesia lacks the heme pathway, it has the PBGS gene forming a tight gene cluster with the SPP gene in the nuclear genome like Toxoplasma, Eimeria, and Plasmodium. Unlike other organisms, Eimeria lacks the intron in the trnL(UAA) gene in the plastid genome

Mentions: Although apicomplexans apparently lack photosynthesis, they have a secondary plastid—the apicoplast (Fig. 1). Because of their clinical, veterinary, or economical importance, disease-related apicomplexans have been extensively researched, and in several instances, both the apicoplast and the nuclear genomes have been sequenced. Metabolisms involving the apicoplast have attracted attention as potential targets for disease-controlling drugs, since they might directly contribute to the survival of the apicomplexan cell. By contrast, housekeeping functions of the organelle have attracted less attention, though they are often unique or significantly different from those of other organisms. In this article, housekeeping functions unique to the apicoplast are mainly discussed.Fig. 1


The apicomplexan plastid and its evolution.

Sato S - Cell. Mol. Life Sci. (2011)

Apicomplexans and the plastid. a Phylogeny of alveolates and distribution of the plastid. The phylogenetic tree was drawn based on the nuclear-encoded 18S rRNA sequences of representative species available in the databases and suggests only topological relationships between taxa. Distribution of the plastid in most Gregarinasina species has not yet been studied (see text). b Phylogeny of the plastids and their variety. Like red plastids (purple), apicoplasts (red, orange, yellow) have the genome encoding sufB, while organisms with green plastids (green) have the gene encoded in the nucleus. Unlike other plastids, the apicoplast genomes lack 5S rRNA gene (rnf). Like other plastid-bearing organisms, Toxoplasma, Eimeria, and Plasmodium have the Suf system incorporating the SufBCD complex, while Babesia and Theileria lack genes specifying the components of the complex. Toxoplasma, Eimeria, and Plasmodium have a unique hybrid-type heme pathway that involves mitochondrial ALA syntase (ALAS). Although Babesia lacks the heme pathway, it has the PBGS gene forming a tight gene cluster with the SPP gene in the nuclear genome like Toxoplasma, Eimeria, and Plasmodium. Unlike other organisms, Eimeria lacks the intron in the trnL(UAA) gene in the plastid genome
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3064897&req=5

Fig1: Apicomplexans and the plastid. a Phylogeny of alveolates and distribution of the plastid. The phylogenetic tree was drawn based on the nuclear-encoded 18S rRNA sequences of representative species available in the databases and suggests only topological relationships between taxa. Distribution of the plastid in most Gregarinasina species has not yet been studied (see text). b Phylogeny of the plastids and their variety. Like red plastids (purple), apicoplasts (red, orange, yellow) have the genome encoding sufB, while organisms with green plastids (green) have the gene encoded in the nucleus. Unlike other plastids, the apicoplast genomes lack 5S rRNA gene (rnf). Like other plastid-bearing organisms, Toxoplasma, Eimeria, and Plasmodium have the Suf system incorporating the SufBCD complex, while Babesia and Theileria lack genes specifying the components of the complex. Toxoplasma, Eimeria, and Plasmodium have a unique hybrid-type heme pathway that involves mitochondrial ALA syntase (ALAS). Although Babesia lacks the heme pathway, it has the PBGS gene forming a tight gene cluster with the SPP gene in the nuclear genome like Toxoplasma, Eimeria, and Plasmodium. Unlike other organisms, Eimeria lacks the intron in the trnL(UAA) gene in the plastid genome
Mentions: Although apicomplexans apparently lack photosynthesis, they have a secondary plastid—the apicoplast (Fig. 1). Because of their clinical, veterinary, or economical importance, disease-related apicomplexans have been extensively researched, and in several instances, both the apicoplast and the nuclear genomes have been sequenced. Metabolisms involving the apicoplast have attracted attention as potential targets for disease-controlling drugs, since they might directly contribute to the survival of the apicomplexan cell. By contrast, housekeeping functions of the organelle have attracted less attention, though they are often unique or significantly different from those of other organisms. In this article, housekeeping functions unique to the apicoplast are mainly discussed.Fig. 1

Bottom Line: Protistan species belonging to the phylum Apicomplexa have a non-photosynthetic secondary plastid-the apicoplast.Although its tiny genome and even the entire nuclear genome has been sequenced for several organisms bearing the organelle, the reason for its existence remains largely obscure.Some of the functions of the apicoplast, including housekeeping ones, are significantly different from those of other plastids, possibly due to the organelle's unique symbiotic origin.

View Article: PubMed Central - PubMed

Affiliation: Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London, UK. ssato@nimr.mrc.ac.uk

ABSTRACT
Protistan species belonging to the phylum Apicomplexa have a non-photosynthetic secondary plastid-the apicoplast. Although its tiny genome and even the entire nuclear genome has been sequenced for several organisms bearing the organelle, the reason for its existence remains largely obscure. Some of the functions of the apicoplast, including housekeeping ones, are significantly different from those of other plastids, possibly due to the organelle's unique symbiotic origin.

Show MeSH