Birth and death of genes and functions in the beta-esterase cluster of Drosophila.
Birth and death of genes and functions in the beta-esterase cluster of Drosophila.
复制标题
果蝇的β-酯酶簇中的基因的出生和死亡。
DOI：
10.1007/s00239-009-9236-3
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发表时间：
2009-07
影响因子：
3.9
通讯作者：
Oakeshott, John G.
中科院分区：
文献类型：
--
作者：
Robin, Charles;Bardsley, Lisa M. J.;Coppin, Chris;Oakeshott, John G.
关键词：
在这里，我们利用最近发布的 12 个果蝇物种的基因组序列分析了果蝇属 β-酯酶基因簇的分子进化。这个小簇中的分子进化值得注意，因为它包含基因功能丧失的类型和阶段的对比例子。具体来说，缺失的直向同源物、假基因和无效等位基因都被推断出来。系统发育分析还表明至少有 9 个基因增益-丢失事件；然而，这些事件的确切数量和年龄因旁系同源重组而变得混乱。先前的一个谜团是，同种异位酶基因座被映射到缺乏催化必需氨基酸的β-酯酶基因，通过识别包含典型催化残基并因此可能编码所映射的同种异位酶的邻近基因，得到了解决。最初发现的基因在选择性约束下进化，表明它们具有“非催化”功能。奇怪的是，D. ananassae 基因组序列中的 4 个旁系同源 β-酯酶基因中有 3 个具有单一失活（移码或无义）突变。为了确定这些假定的失活突变是否已被修复，我们对这四个基因座的其他 D. ananassae 等位基因进行了测序。我们在其他 12 个菌株中没有发现已测序菌株的 3 个失活突变；然而，在这 3 个基因中还观察到了其他失活突变。这让人想起在黑腹果蝇的 β-酯酶基因之一 (Est7/EstP) 中观察到的高频率无效等位基因。本文的在线版本 (doi:10.1007/s00239-009-9236-3) 包含补充材料，可供授权用户使用。
Here we analyze the molecular evolution of the β-esterase gene cluster in the Drosophila genus using the recently released genome sequences of 12 Drosophila species. Molecular evolution in this small cluster is noteworthy because it contains contrasting examples of the types and stages of loss of gene function. Specifically, missing orthologs, pseudogenes, and null alleles are all inferred. Phylogenetic analyses also suggest a minimum of 9 gene gain–loss events; however, the exact number and age of these events is confounded by interparalog recombination. A previous enigma, in which allozyme loci were mapped to β-esterase genes that lacked catalytically essential amino acids, was resolved through the identification of neighbouring genes that contain the canonical catalytic residues and thus presumably encode the mapped allozymes. The originally identified genes are evolving with selective constraint, suggesting that they have a “noncatalytic” function. Curiously, 3 of the 4 paralogous β-esterase genes in the D. ananassae genome sequence have single inactivating (frame-shift or nonsense) mutations. To determine whether these putatively inactivating mutations were fixed, we sequenced other D. ananassae alleles of these four loci. We did not find any of the 3 inactivating mutations of the sequenced strain in 12 other strains; however, other inactivating mutations were observed in the same 3 genes. This is reminiscent of the high frequency of null alleles observed in one of the β-esterase genes (Est7/EstP) of D. melanogaster. The online version of this article (doi:10.1007/s00239-009-9236-3) contains supplementary material, which is available to authorized users.
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