Spot 42 RNA mediates discoordinate expression of the E-coli galactose operon
Spot 42 RNA mediates discoordinate expression of the E-coli galactose operon
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DOI：
10.1101/gad.231702
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发表时间：
2002-07-01
影响因子：
10.5
通讯作者：
Valentin-Hansen, P
中科院分区：
文献类型：
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作者：
Moller, T;Franch, T;Valentin-Hansen, P
大肠杆菌Spot 42 RNA的生理作用仍然不清楚，尽管109个核苷酸的RNA在近30年前被发现。斑点42 RNA的结构特征和以前的工作向我们表明，RNA可能是半乳糖操纵子的不协调基因表达的调节剂，这种控制仅在现象学水平上被理解。控制Spot 42 RNA的表达或删除编码RNA的基因（spf）的效果支持了这一假设。galK表达的下调，在半乳糖操纵子中的第三个基因，只观察到斑点42 RNA的存在下，所需的生长条件，引起的spf基因的去阻遏。随后的生物化学研究表明，Spot 42 RNA特异性结合在galETKM mRNA的galK Shine-Dalgarno区域，从而阻断核糖体结合。我们得出的结论是，Spot 42 RNA是一种反义RNA，其作用是差异调节从相同转录单位表达的基因。我们的研究结果揭示了一个有趣的机制，启动子远端基因在操纵子中的表达可以被调节，并强调了反义控制在细菌基因调控中的重要性。
The physiological role of Escherichia coli Spot 42 RNA has remained obscure, even though the 109-nucleotide RNA was discovered almost three decades ago. Structural features of Spot 42 RNA and previous work suggested to us that the RNA might be a regulator of discoordinate gene expression of the galactose operon, a control that is only understood at the phenomenological level. The effects of controlled expression of Spot 42 RNA or deleting the gene (spf) encoding the RNA supported this hypothesis. Down-regulation of galK expression, the third gene in the gal operon, was only observed in the presence of Spot 42 RNA and required growth conditions that caused derepression of the spf gene. Subsequent biochemical studies showed that Spot 42 RNA specifically bound at the galK Shine-Dalgarno region of the galETKM mRNA, thereby blocking ribosome binding. We conclude that Spot 42 RNA is an antisense RNA that acts to differentially regulate genes that are expressed from the same transcription unit. Our results reveal an interesting mechanism by which the expression of a promoter distal gene in an operon can be modulated and underline the importance of antisense control in bacterial gene regulation.