Department of Metabolic Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom; email:
Current affiliation: Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom; email:
Annu Rev Genet. 2018 Nov 23;52:159-183. doi: 10.1146/annurev-genet-120417-031237. Epub 2018 Sep 5.
In bacteria, more than half of the genes in the genome are organized in operons. In contrast, in eukaryotes, functionally related genes are usually dispersed across the genome. There are, however, numerous examples of functional clusters of nonhomologous genes for metabolic pathways in fungi and plants. Despite superficial similarities with operons (physical clustering, coordinate regulation), these clusters have not usually originated by horizontal gene transfer from bacteria, and (unlike operons) the genes are typically transcribed separately rather than as a single polycistronic message. This clustering phenomenon raises intriguing questions about the origins of clustered metabolic pathways in eukaryotes and the significance of clustering for pathway function. Here we review metabolic gene clusters from fungi and plants, highlight commonalities and differences, and consider how these clusters form and are regulated. We also identify opportunities for future research in the areas of large-scale genomics, synthetic biology, and experimental evolution.
在细菌中，基因组中的基因有一半以上组织在操纵子中。相比之下，在真核生物中，功能相关的基因通常分散在基因组中。然而，在真菌和植物中，代谢途径的非同源基因的功能簇有许多例子。尽管与操纵子（物理聚类、协调调节）有表面相似之处，但这些簇通常不是由来自细菌的水平基因转移产生的，而且（与操纵子不同）这些基因通常是单独转录的，而不是作为单个多顺反子消息转录的。这种聚类现象引发了关于真核生物中聚类代谢途径的起源以及聚类对途径功能的意义的有趣问题。在这里，我们回顾了真菌和植物中的代谢基因簇，强调了它们的共性和差异，并考虑了这些簇是如何形成和被调控的。我们还确定了在大规模基因组学、合成生物学和实验进化等领域未来研究的机会。
