Did homeodomain proteins duplicate before the origin of angiosperms, fungi, and metazoa?
Did homeodomain proteins duplicate before the origin of angiosperms, fungi, and metazoa?
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DOI：
10.1073/pnas.94.25.13749
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发表时间：
1997-12-09
影响因子：
11.1
通讯作者：
Sinha, N
中科院分区：
文献类型：
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作者：
Bharathan, G;Janssen, BJ;Sinha, N
同源结构域蛋白是在真核生物早期发育中起关键作用的转录因子。这些蛋白质以前被分成许多亚类，它们的系统发育关系尚不清楚。我们对具有代表性的真核生物序列的系统发育分析表明，有两类主要的同源结构域蛋白，每一组都包含被子植物、后生动物和真菌的序列。这一结果基于对初级氨基酸序列的简约和邻接分析，得到了蛋白质的两个额外特征的支持。这两个蛋白质组通过在同源结构域、螺旋I和螺旋II之间的插入/缺失来区分。此外，同源结构域N端的两亲性α-螺旋二级结构由被子植物和后生动物序列在一个组中共享。这些结果支持这样的假设，即在被子植物、真菌和后生动物起源之前，至少有一次同源框基因的重复。这种重复反过来又表明，这些蛋白质在真核生物进化的早期具有不同的功能。被子植物和后生动物序列中共有的二级结构指向一个古老的保守功能结构域。
Homeodomain proteins are transcription factors that play a critical role in early development in eukaryotes. These proteins previously have been classified into numerous subgroups whose phylogenetic relationships are unclear. Our phylogenetic analysis of representative eukaryotic sequences suggests that there are two major groups of homeodomain proteins, each containing sequences from angiosperms, metazoa, and fungi. This result, based on parsimony and neighbor-joining analyses of primary amino acid sequences, was supported by two additional features of the proteins. The two protein groups are distinguished by an insertion/deletion in the homeodomain, between helices I and II. In addition, an amphipathic alpha-helical secondary structure in the region N terminal of the homeodomain is shared by angiosperm and metazoan sequences in one group. These results support the hypothesis that there was at least one duplication of homeobox genes before the origin of angiosperms, fungi, and metazoa. This duplication, in turn, suggests that these proteins had diverse functions early in the evolution of eukaryotes. The shared secondary structure in angiosperm and metazoan sequences points to an ancient conserved functional domain.