A receptor tyrosine kinase from choanoflagellates: Molecular insights into early animal evolution
A receptor tyrosine kinase from choanoflagellates: Molecular insights into early animal evolution
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DOI：
10.1073/pnas.261477698
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发表时间：
2001-12-18
影响因子：
11.1
通讯作者：
Carroll, SB
中科院分区：
文献类型：
--
作者：
King, N;Carroll, SB
后生动物从原生动物进化而来是生命史上的一个重要里程碑。这种进化转变中涉及的遗传和发育事件尚不清楚，但可能涉及后生动物中信号传导和基因调控所需基因的进化。动物祖先的基因组可以通过鉴定与相关真核生物共享的动物基因来重建，特别是那些与动物共享更近的祖先和细胞生物学的基因。长期以来，人们一直怀疑领鞭毛虫与动物的亲缘关系比真菌更近，真菌是可获得比较基因组信息的最接近的外类群动物。然而，基于小亚基rDNA序列的领鞭藻和动物关系的系统发育分析产生了模糊和相互矛盾的结果。我们发现，四个保守的蛋白质从单细胞的choanoflagellate，Monosiga brevicollis，提供了强有力的支持choanoflagellates和后生动物之间的密切关系，这表明比较互补的表达基因从choanoflagellates和动物可能是信息有关后生动物基因组的早期进化。我们发现在M。brevicollis的第一个受体酪氨酸激酶（RTK），据我们所知，确定以外的后生动物，MBRTK1。MBRTK1的结构包括多个细胞外配体结合结构域，类似于海绵和人类中的RTK，并表明具有接收和抑制信号的能力。因此，领鞭毛虫表达参与动物发育的基因，这些基因在其他真核生物中没有发现，并且可能与后生动物的起源有关。
The evolution of the Metazoa from protozoans is one of the major milestones in life's history. The genetic and developmental events involved in this evolutionary transition are unknown but may have involved the evolution of genes required for signaling and gene regulation in metazoans. The genome of animal ancestors may be reconstructed by identification of animal genes that are shared with related eukaryotes, particularly those that share a more recent ancestry and cell biology with animals. The choanoflagellates have long been suspected to be closer relatives of animals than are fungi, the closest outgroup of animals for which comparative genomic information is available. Phylogenetic analyses of choanoflagellate and animal relationships based on small subunit rDNA sequence, however, have yielded ambiguous and conflicting results. We find that analyses of four conserved proteins from a unicellular choanoflagellate, Monosiga brevicollis, provide robust support for a close relationship between choanoflagellates and Metazoa, suggesting that comparison of the complement of expressed genes from choanoflagellates and animals may be informative concerning the early evolution of metazoan genomes. We have discovered in M. brevicollis the first receptor tyrosine kinase (RTK), to our knowledge, identified outside of the Metazoa, MBRTK1. The architecture of MBRTK1, which includes multiple extracellular ligand-binding domains, resembles that of RTKs in sponges and humans and suggests the ability to receive and transduce signals. Thus, choanoflagellates express genes involved in animal development that are not found in other eukaryotes and that may be linked to the origin of the Metazoa.