Orthologs and paralogs of regA, a master cell-type regulatory gene in Volvox carteri
Orthologs and paralogs of regA, a master cell-type regulatory gene in Volvox carteri
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DOI：
10.1007/s00294-006-0071-4
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发表时间：
2006-07-01
期刊：
影响因子：
2.5
通讯作者：
Miller, Stephen M.
中科院分区：
文献类型：
--
作者：
Duncan, Leonard;Nishii, Ichiro;Miller, Stephen M.
多细胞绿藻Volvox carteri forma nagariensis只有两种细胞类型：终末分化的体细胞和生殖细胞。 regA 基因显然是通过抑制叶绿体生物发生所需基因的转录来维持体细胞的终末分化状态，从而阻止细胞生长。由于 RegA 蛋白序列没有明显的基序，我们试图通过在 RegA 直系同源物中寻找高度保守的结构域来识别具有重要功能的区域。在这里，我们报告了来自最密切相关的已知分类单元 V. carteri f 的 regA 的克隆和表征。川崎病。考虑到这两种形式之间的密切关系，它们的 regA 基因有着惊人的不同：它们的内含子数量和几个较长的插入缺失有所不同，而且它们编码的蛋白质只有 80% 相同。我们还偶然发现了每个 regA 位点上游紧邻的旁系同源基因。这两个 regA 基因都是上游旁系同源物，也是衣藻（Volvox 最接近的单细胞亲戚）中的几个基因，编码一个保守区域（VARL 结构域），其中包含似乎是 DNA 结合 SAND 结构域。这一发现为探索 regA 及其控制的终末分化状态如何进化开辟了新途径。
The multicellular green alga Volvox carteri forma nagariensis has only two cell types: terminally differentiated somatic cells and reproductive cells. The regA gene maintains the terminally differentiated state of the somatic cells, apparently by repressing transcription of genes required for chloroplast biogenesis and thereby preventing cell growth. Because the RegA protein sequence bore no obvious motifs, we are attempting to identify regions of functional importance by searching for strongly conserved domains in RegA orthologs. Here we report the cloning and characterization of regA from the most closely related known taxon, V. carteri f. kawasakiensis. Given the closeness of the relationship between these two formas, their regA genes are surprisingly different: they differ in the number of introns and by several lengthy indels, and they encode proteins that are only 80% identical. We also serendipitously discovered a paralogous gene immediately upstream of each regA locus. The two regA genes, both upstream paralogs and several genes in Chlamydomonas (the closest unicellular relative of Volvox) encode a conserved region (the VARL domain) that contains what appears to be a DNA-binding SAND domain. This discovery has opened up a new avenue for exploring how regA and the terminally differentiated state that it controls evolved.