The evolutionary origin of the 35 kb circular DNA of Plasmodium falciparum: new evidence supports a possible rhodophyte ancestry
1994
Williamson, D.H. (National Inst. for Medical Research, London (United Kingdom)) | Gardner, M.J. | Preiser, P. | Moore, D.J. | Rangachari, K. | Wilson, R.J.M.
In common with other Apicomplexan parasites, Plasmodium falciparum carries two extrachromosomal DNAs, one of which, the 6 kb element, is undoubtedly mitochondrial. The second, generally referred to as the 35 kb circle, is of unknown provenance, but the nature and organization of its genetic content makes a mitochondrial association unlikely and the molecule has features reminiscent of plastid genomes. The occurrence on the circle of an open reading frame is reported specifying a predicted 470 amino acid protein that shares more than 50% identity with a gene currently known only on the plastome of red algae. This high degree of conservation confirms the 35 kb circle's plastid ancestry, and it is speculated that it may have originated from the rhodoplast of an ancient red algal endosymbiont in the progenitor of the Apicomplexa.
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