Endosymbiotic origin and differential loss of eukaryotic genes
Endosymbiotic origin and differential loss of eukaryotic genes
复制标题
DOI：
10.1038/nature14963
复制
发表时间：
2015-08-27
期刊：
影响因子：
64.8
通讯作者：
Martin, William F.
中科院分区：
文献类型：
--
作者：
Ku, Chuan;Nelson-Sathi, Shijulal;Martin, William F.
叶绿体源自蓝细菌，线粒体源自变形菌。这两种细胞器都保留了原核生物化学，但它们的基因组减少了，并且大多数细胞器蛋白在细胞核中编码。内共生理论认为，真核基因组中的细菌基因通过细胞器祖先进入真核谱系。它预测原核基因间歇性流入真核谱系，并获得与内共生事件相对应的基因。然而，真核基因组序列越来越多地涉及从原核生物到真核生物以及真核生物之间的横向基因转移，作为真核基因组中基因内容变异的来源，这预示着不同真核群体中原核基因的连续、谱系特异性获得。在这里，我们通过对具有原核同源物的真核基因家族进行聚类和系统发育分析来区分这两种选择。我们的结果表明（1）从细菌到真核生物的基因转移是间歇性的，正如基因分布所揭示的那样，并且与叶绿体和线粒体起源的主要进化转变相一致； （2）真核生物的基因遗传是垂直的，广泛的拓扑比较表明，差异丢失导致基因分布稀疏； (3)连续的、谱系特异性的横向基因转移虽然有时会发生，但对真核基因组中的长期基因内容进化没有贡献。
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.