Ben-Shahar Yehuda, Nannapaneni Kishore, Casavant Thomas L, Scheetz Todd E, Welsh Michael J
Howard Hughes Medical Institute, and Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine Center for Bioinformatics and Computational Biology, University of Iowa, Iowa City, IA 52242, USA.
Proc Natl Acad Sci U S A. 2007 Jan 2;104(1):222-7. doi: 10.1073/pnas.0609683104. Epub 2006 Dec 26.
Complex biological processes require coordinated function of many genes. One evolutionary solution to the problem of coordinately expressing functionally related genes in bacteria and nematodes is organization of genes in operons. Surprisingly, eukaryotic operons are considered rare outside the nematode lineage. In Drosophila melanogaster, we found lounge lizard (llz), which encodes a degenerin/ENaC cation channel, cotranscribed with CheB42a, a nonhomologous gene of unknown function residing <100 bp upstream. These two genes were transcribed from a single promoter as one primary transcript and were processed posttranscriptionally to generate individual mRNAs. The mechanism did not involve alternative splicing, and it differed from the trans splicing used in nematode operons. Both genes were expressed in the same tissues, and previous work suggested that both may be involved in courtship behavior. A bioinformatic approach identified numerous additional loci as potential Drosophila operons. These data reveal eukaryotic operon-like transcription of functionally related genes in Drosophila. The results also suggest that operon-based transcription may be more common in eukaryotes than previously appreciated.
复杂的生物过程需要许多基因的协同作用。在细菌和线虫中，协调表达功能相关基因问题的一种进化解决方案是基因成簇排列在操纵子中。令人惊讶的是，在线虫谱系之外，真核生物操纵子被认为很罕见。在黑腹果蝇中，我们发现了“休闲蜥蜴”（llz）基因，它编码一种退化蛋白/上皮钠通道，与CheB42a基因共同转录，CheB42a是一个功能未知的非同源基因，位于llz基因上游不到100个碱基对处。这两个基因从一个单一启动子转录为一个初级转录本，并在转录后进行加工以产生各自的信使核糖核酸。该机制不涉及可变剪接，并且与线虫操纵子中使用的反式剪接不同。这两个基因在相同组织中表达，先前的研究表明它们可能都参与求偶行为。一种生物信息学方法鉴定出许多其他基因座作为潜在的果蝇操纵子。这些数据揭示了果蝇中功能相关基因的真核生物类操纵子转录。结果还表明，基于操纵子的转录在真核生物中可能比以前认为的更为普遍。
