Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs
2012 (English)In: Nature, ISSN 0028-0836, Vol. 492, no 7427, 59-65 p.Article in journal (Refereed) Published
Cryptophyte and chlorarachniophyte algae are transitional forms in the widespread secondary endosymbiotic acquisition of photosynthesis by engulfment of eukaryotic algae. Unlike most secondary plastid-bearing algae, miniaturized versions of the endosymbiont nuclei (nucleomorphs) persist in cryptophytes and chlorarachniophytes. To determine why, and to address other fundamental questions about eukaryote-eukaryote endosymbiosis, we sequenced the nuclear genomes of the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans. Both genomes have >21,000 protein genes and are intron rich, and B. natans exhibits unprecedented alternative splicing for a single-celled organism. Phylogenomic analyses and subcellular targeting predictions reveal extensive genetic and biochemical mosaicism, with both host-and endosymbiont-derived genes servicing the mitochondrion, the host cell cytosol, the plastid and the remnant endosymbiont cytosol of both algae. Mitochondrion-to-nucleus gene transfer still occurs in both organisms but plastid-to-nucleus and nucleomorph-to-nucleus transfers do not, which explains why a small residue of essential genes remains locked in each nucleomorph.
Place, publisher, year, edition, pages
2012. Vol. 492, no 7427, 59-65 p.
IdentifiersURN: urn:nbn:se:uu:diva-190314DOI: 10.1038/nature11681ISI: 000311893400045OAI: oai:DiVA.org:uu-190314DiVA: diva2:585934