Details

Autor(en) / Beteiligte

• Ku, Chuan
• Nelson-Sathi, Shijulal
• Roettger, Mayo
• Sousa, Filipa L.
• Lockhart, Peter J.
• Bryant, David
• Hazkani-Covo, Einat
• McInerney, James O.
• Landan, Giddy
• Martin, William F.

Titel

Endosymbiotic origin and differential loss of eukaryotic genes

Ist Teil von

• Nature (London), 2015-08, Vol.524 (7566), p.427-432

Ort / Verlag

London: Nature Publishing Group UK

Erscheinungsjahr

2015

Quelle

EBSCOhost Psychology and Behavioral Sciences Collection

Beschreibungen/Notizen

• Chloroplasts arose from cyanobacteria, mitochondria arose from proteobacteria. Both organelles have conserved their prokaryotic biochemistry, but their genomes are reduced, and most organelle proteins are encoded in the nucleus. Endosymbiotic theory posits that bacterial genes in eukaryotic genomes entered the eukaryotic lineage via organelle ancestors. It predicts episodic influx of prokaryotic genes into the eukaryotic lineage, with acquisition corresponding to endosymbiotic events. Eukaryotic genome sequences, however, increasingly implicate lateral gene transfer, both from prokaryotes to eukaryotes and among eukaryotes, as a source of gene content variation in eukaryotic genomes, which predicts continuous, lineage-specific acquisition of prokaryotic genes in divergent eukaryotic groups. Here we discriminate between these two alternatives by clustering and phylogenetic analysis of eukaryotic gene families having prokaryotic homologues. Our results indicate (1) that gene transfer from bacteria to eukaryotes is episodic, as revealed by gene distributions, and coincides with major evolutionary transitions at the origin of chloroplasts and mitochondria; (2) that gene inheritance in eukaryotes is vertical, as revealed by extensive topological comparison, sparse gene distributions stemming from differential loss; and (3) that continuous, lineage-specific lateral gene transfer, although it sometimes occurs, does not contribute to long-term gene content evolution in eukaryotic genomes. Eukaryotes acquired their prokaryotic genes in two episodes of evolutionary influx corresponding to the origin of mitochondria and plastids, respectively, followed by extensive differential gene loss, uncovering a massive imprint of endosymbiosis in the nuclear genomes of complex cells. Origin of prokaryote genes in eukaryotes For many years it has been assumed that the prokaryote genes found in eukaryote genomes must have got there after endosymbiosis of a prokaryotic organelle. But recent evidence has suggested there is also substantial lateral gene transfer among eukaryotes and between prokaryotes and eukaryotes. This analysis of bacterial, archaeal and eukaryotic genomes finds no evidence for a detectable cumulative impact of continuous lateral gene transfer on the evolution of eukaryote gene content. Rather, eukaryotes acquired their prokaryotic genes in two episodes of evolutionary influx corresponding to the origin of the mitochondria and plastids, followed by extensive differential gene loss. This history has left a massive imprint of endosymbiosis in the nuclear genomes of complex cells.