A new scrambled gene in the ciliate Uroleptus
A new scrambled gene in the ciliate Uroleptus
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DOI：
10.1016/j.gene.2005.10.008
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发表时间：
2006-03-01
期刊：
影响因子：
3.5
通讯作者：
Landweber, LF
中科院分区：
文献类型：
--
作者：
Chang, WJ;Kuo, S;Landweber, LF
在旋毛纤毛虫的生殖细胞微核中，产生体细胞大核的基因片段或大核预定序列（MI）被内部消除序列（IES）中断。对于某些基因，MDS在微核中不是顺序排列的，而是杂乱排列的。三个乱序基因已在许多物种中被广泛研究：肌动蛋白I，α-端粒结合蛋白和DNA聚合酶α。然而，在过去的十年中，没有新的乱序基因的报道，乱序基因的流行仍然是一个重要的问题。为了筛选乱序基因，我们对旋螺属Uroleptus sp.的11条大核染色体进行了完全测序，然后继续研究他们的微核组织。这使我们能够识别新的乱序基因，这些基因也显示出新的特征。在这项研究中，我们描述了这些新发现的乱序基因之一。该基因暂命名为USG 1（Unknown Scrambled Gene 1），编码一个1016个氨基酸的蛋白质。虽然该蛋白产物的功能尚不清楚，但从两个等位基因计算的dN/dS表明编码的蛋白质处于纯化选择中。USGI由16个生殖系MDS组成，其中14个位于一个基因座上。另一个基因座，这是至少3 kb远离主基因座，包含两个乱序MDS分开的nonscrambled IES。奇怪的是，一个MDS和它的外向（3 '）指针（直接重复）重叠内含子剪接位点，表明这些DNA序列可能受到双重（或多重）约束。我们的研究结果确定了一个新的乱序基因的spirotrichous纤毛虫的微核基因组，并建议，甚至更复杂的结构可能存在。(c)2005 Elsevier B. V.保留所有权利。
In the germline micronucleus of spirotrichous ciliates, the gene segments, or macronuclear destined sequences (MI)Ss), that give rise to the somatic macronucleus are interrupted by internal eliminated sequences (IESs). For some genes, the MDSs are not arranged sequentially, but rather are scrambled, in the micronucleus. Three scrambled genes have been extensively studied in many species: actin I, alpha-telomere binding protein, and DNA polymerase alpha. However, in the past decade, no new scrambled genes have been reported, and the prevalence of scrambled genes is still an important question. To screen for scrambled genes, we completely sequenced 11 macronuclear chromosomes in the spirotrich Uroleptus sp., and then pursued their micronuclear organization. This allowed us to identify new scrambled genes, which also display novel features. In this study we describe one of these newly discovered scrambled genes. This gene, tentatively named USG1 (Unknown Scrambled Gene 1), encodes a putative protein of 1016 aa. While the function of this protein product is not clear, dN/dS calculated from the two alleles suggests the encoded protein is under purifying selection. USGI consists of 16 germline MDSs, of which 14 are located on one locus. The other locus, which is at least 3 kb away from the main locus, contains two scrambled MDSs separated by a nonscrambled IES. Curiously, one MDS and its outgoing (3') pointer (direct repeat) overlap intron splice sites, indicating that these DNA sequences may be under dual (or multiple) constraints. Our findings identify a new scrambled gene in the micronuclear genome of a spirotrichous ciliate, and suggest that even more complicated structures may be present. (c) 2005 Elsevier B.V. All rights reserved.