EFL GTPase in Cryptomonads and the Distribution of EFL and EF-1α in Chromalveolates

Gillian H. Gile, Nicola J. Patron, Patrick J. Keeling

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

EFL (EF-like protein) is a member of the GTPase superfamily that includes several translation factors. Because it has only been found in a few eukaryotic lineages and its presence correlates with the absence of the related core translation factor EF-1α, its distribution is hypothesized to be the result of lateral gene transfer and replacement of EF-1α. In one supergroup of eukaryotes, the chromalveolates, two major lineages were found to contain EFL (dinoflagellates and haptophytes), while the others encode EF-1α (apicomplexans, ciliates, heterokonts and cryptomonads). For each of these groups, this distribution was deduced from whole genome sequence or expressed sequence tag (EST) data from several species, with the exception of cryptomonads from which only a single EF-1α PCR product from one species was known. By sequencing ESTs from two cryptomonads, Guillardia theta and Rhodomonas salina, and searching for all GTPase translation factors, we revealed that EFL is present in both species, but, contrary to expectations, we found EF-1α in neither. On balance, we suggest the previously reported EF-1α from Rhodomonas salina is likely an artefact of contamination. We also identified EFL in EST data from two members of the dinoflagellate lineage, Karlodinium micrum and Oxyrrhis marina, and from an ongoing genomic sequence project from a third, Perkinsus marinus. Karlodinium micrum is a symbiotic pairing of two lineages that would have both had EFL (a dinoflagellate and a haptophyte), but only the dinoflagellate gene remains. Oxyrrhis marina and Perkinsus marinus are early diverging sister-groups to dinoflagellates, and together show that EFL originated early in this lineage. Phylogenetic analysis confirmed that these genes are all EFL homologues, and showed that cryptomonad genes are not detectably related to EFL from other chromalveolates, which collectively form several distinct groups. The known distribution of EFL now includes a third group of chromalveolates, cryptomonads. Of the six major subgroups of chromalveolates, EFL is found in half and EF-1α in the other half, and none as yet unambiguously possess both genes. Phylogenetic analysis indicates EFL likely arose early within each subgroup where it is found, but suggests it may have originated multiple times within chromalveolates as a whole.

Original languageEnglish (US)
Pages (from-to)435-444
Number of pages10
JournalProtist
Volume157
Issue number4
DOIs
StatePublished - Oct 24 2006
Externally publishedYes

Keywords

  • Chromalveolates
  • cryptomonads
  • dinoflagellates
  • lateral gene transfer
  • translation factor

ASJC Scopus subject areas

  • Microbiology

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