A hypothesis for the evolution of nuclear-encoded, plastid-targeted glyceraldehyde-3-phosphate dehydrogenase genes in "chromalveolate" members.
Eukaryotes bearing red alga-derived plastids--photosynthetic alveolates (dinoflagellates plus the apicomplexan Toxoplasma gondii plus the chromerid Chromera velia), photosynthetic stramenopiles, haptophytes, and cryptophytes--possess unique plastid-targeted glyceraldehyde-3-phosphate dehydrogenases (henceforth designated as "GapC1"). Pioneering phylogenetic studies have indicated a single origin of the GapC1 enzymes in eukaryotic evolution, but there are two potential idiosyncrasies in the GapC1 phylogeny: Firstly, the GapC1 tree topology is apparently inconsistent with the organismal relationship among the "GapC1-containing" groups. Secondly, four stramenopile GapC1 homologues are consistently paraphyletic in previously published studies, although these organisms have been widely accepted as monophyletic. For a closer examination of the above issues, in this study GapC1 gene sampling was improved by determining/identifying nine stramenopile and two cryptophyte genes. Phylogenetic analyses of our GapC1 dataset, which is particularly rich in the stramenopile homologues, prompt us to propose a new scenario that assumes multiple, lateral GapC1 gene transfer events to explain the incongruity between the GapC1 phylogeny and the organismal relationships amongst the "GapC1-containing" groups. Under our new scenario, GapC1 genes uniquely found in photosynthetic alveolates, photosynthetic stramenopiles, haptophytes, and cryptopyhytes are not necessarily a character vertically inherited from a common ancestor.
Takishita
Kiyotaka
K
Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan. takishitak@jamstec.go.jp
Yamaguchi
Haruyo
H
Maruyama
Tadashi
T
Inagaki
Yuji
Y
D002467:Cell Nucleus / Q000235:genetics*; D056890:Eukaryota / Q000145:classification / Q000201:enzymology / Q000235:genetics*; D019143:Evolution, Molecular; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D018087:Plastids / Q000201:enzymology / Q000235:genetics*
D005987:Glyceraldehyde-3-Phosphate Dehydrogenases