Characterization of a Conserved Extrachromosomal Element Isolated from the Avian Malarial Parasite <i>Plasmodium gallinaceum</i>

Joseph, Jomon; Aldritt, S M; Unnasch, Thomas R.; Puijalon, Odile; Wirth, Dyann F.

doi:10.1128/mcb.9.9.3621-3629.1989

Cited by 15 publications

(3 citation statements)

References 44 publications

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“…The 6 kb element was estimated at the time to exist in about 20 copies per cell in P. falciparum. This coincides with the copy number reported for P. gallinaceum (15-20/cell) (Joseph et al, 1989), but is markedly lower than the number of copies reported for P. yoelii (150/cell) (Vaidya and Arasu, 1987). The biological significance of these differences remains unclear.…”

Section: The Mitochondria Of Apicomplexanssupporting

confidence: 78%

“…Hybridization experiments elegantly demonstrated that the 6 kb element did not exist as a linear monomer, but rather exists within tandem arrays of varying sizes. These tandems range from 6 to 30 kb, with a marked preponderance of dimers of 12 kb (Joseph et al, 1989). Preiser and colleagues showed in 1996, through fine analyses of the mitogenome configuration of P. falciparum, using 2D gels, that circular topologies observed by electron microscopy of isolated mitochondrial DNA constitute a minor fraction of the molecules.…”

Section: The Mitochondria Of Apicomplexansmentioning

confidence: 99%

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The Elusive Mitochondrial Genomes of Apicomplexa: Where Are We Now?

2021

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Mitochondria are vital organelles of eukaryotic cells, participating in key metabolic pathways such as cellular respiration, thermogenesis, maintenance of cellular redox potential, calcium homeostasis, cell signaling, and cell death. The phylum Apicomplexa is entirely composed of obligate intracellular parasites, causing a plethora of severe diseases in humans, wild and domestic animals. These pathogens include the causative agents of malaria, cryptosporidiosis, neosporosis, East Coast fever and toxoplasmosis, among others. The mitochondria in Apicomplexa has been put forward as a promising source of undiscovered drug targets, and it has been validated as the target of atovaquone, a drug currently used in the clinic to counter malaria. Apicomplexans present a single tubular mitochondria that varies widely both in structure and in genomic content across the phylum. The organelle is characterized by massive gene migrations to the nucleus, sequence rearrangements and drastic functional reductions in some species. Recent third generation sequencing studies have reignited an interest for elucidating the extensive diversity displayed by the mitochondrial genomes of apicomplexans and their intriguing genomic features. The underlying mechanisms of gene transcription and translation are also ill-understood. In this review, we present the state of the art on mitochondrial genome structure, composition and organization in the apicomplexan phylum revisiting topological and biochemical information gathered through classical techniques. We contextualize this in light of the genomic insight gained by second and, more recently, third generation sequencing technologies. We discuss the mitochondrial genomic and mechanistic features found in evolutionarily related alveolates, and discuss the common and distinct origins of the apicomplexan mitochondria peculiarities.

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Section: The Mitochondria Of Apicomplexanssupporting

confidence: 78%

Section: The Mitochondria Of Apicomplexansmentioning

confidence: 99%

The Elusive Mitochondrial Genomes of Apicomplexa: Where Are We Now?

2021

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“…The discovery of mitochondrial DNA (mtDNA) in malaria parasites as tandemly arrayed molecules with a unit length of 6 kb (51,120,(125)(126)(127) led to the realization that a separate circular DNA of 35 kb in the parasite, then believed to be an mtDNA (34,135), was in fact a remnant of a chloroplast genome residing in a separate organelle, now termed an apicoplast (for apicomplexan plastid). The apicoplast consists of a four-membrane structure and thus is proposed to have originated from a secondary endosymbiotic event common to all apicomplexans, in which an algal organism was engulfed by the progenitor of both the dinoflagellates and apicomplexans (56,57).…”

Section: Introductionmentioning

confidence: 99%

Unique Properties of Apicomplexan Mitochondria

Lamb

Okoye

Mather

et al. 2023

Annu. Rev. Microbiol.

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Apicomplexan parasites constitute more than 6,000 species infecting a wide range of hosts. These include important pathogens such as those causing malaria and toxoplasmosis. Their evolutionary emergence coincided with the dawn of animals. Mitochondrial genomes of apicomplexan parasites have undergone dramatic reduction in their coding capacity, with genes for only three proteins and ribosomal RNA genes present in scrambled fragments originating from both strands. Different branches of the apicomplexans have undergone rearrangements of these genes, with Toxoplasma having massive variations in gene arrangements spread over multiple copies. The vast evolutionary distance between the parasite and the host mitochondria has been exploited for the development of antiparasitic drugs, especially those used to treat malaria, wherein inhibition of the parasite mitochondrial respiratory chain is selectively targeted with little toxicity to the host mitochondria. We describe additional unique characteristics of the parasite mitochondria that are being investigated and provide greater insights into these deep-branching eukaryotic pathogens. Expected final online publication date for the Annual Review of Microbiology, Volume 77 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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A 7.1 kb linear DNA molecule of Theileria parva has scrambled rDNA sequences and open reading frames for mitochondrially encoded proteins.

et al. 1994

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Theileria parva, an intralymphocytic protozoan parasite of cattle, contains a linear 7.1 kb DNA element with terminal inverted repeat sequences. The molecule is transcribed into low molecular weight RNA, and both DNA strands encode short stretches of unique sequences, usually < 100 nucleotides, which are similar to large (LSU) or small (SSU) ribosomal subunit RNA. Phylogenetically conserved conformational rRNA domains were assembled from the discontinuous rDNA sequences using comparative secondary structure modelling. For example, a minimum of four predicted sequences, two derived from each DNA strand, is required to assemble domain V of LSU rRNA which participates in peptidyl transferase activity. The discontinuities in the identified rRNA domains fall within regions of no known functional significance. Hence, it is likely that the element encodes fragmented rDNA genes and the mature rRNA is unconventional, consisting of several fragments of RNA, primarily held together by intermolecular and intramolecular base pairing. The element also has ORFs for components of the last two mitochondrial electron transport enzyme complexes. The structure of the parasite DNA element, its protein coding capacity and scrambled rDNA gene sequences, are reminiscent of the mitochondrial genome of Chlamydomonas reinhardtii. We propose that the 7.1 kb element is equivalent to the mitochondrial DNA of T. parva, although a number of its features are unusual for this family of extrachromosomal DNA molecules.

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Characterization of a Conserved Extrachromosomal Element Isolated from the Avian Malarial Parasite Plasmodium gallinaceum

Cited by 15 publications

References 44 publications

The Elusive Mitochondrial Genomes of Apicomplexa: Where Are We Now?

The Elusive Mitochondrial Genomes of Apicomplexa: Where Are We Now?

Unique Properties of Apicomplexan Mitochondria

A 7.1 kb linear DNA molecule of Theileria parva has scrambled rDNA sequences and open reading frames for mitochondrially encoded proteins.

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