Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892-5430, USA.
Mol Cell. 2011 Feb 4;41(3):286-97. doi: 10.1016/j.molcel.2010.12.027.
Bacteria selectively consume some carbon sources over others through a regulatory mechanism termed catabolite repression. Here, we show that the base-pairing RNA Spot 42 plays a broad role in catabolite repression in Escherichia coli by directly repressing genes involved in central and secondary metabolism, redox balancing, and the consumption of diverse nonpreferred carbon sources. Many of the genes repressed by Spot 42 are transcriptionally activated by the global regulator CRP. Since CRP represses Spot 42, these regulators participate in a specific regulatory circuit called a multioutput feedforward loop. We found that this loop can reduce leaky expression of target genes in the presence of glucose and can maintain repression of target genes under changing nutrient conditions. Our results suggest that base-pairing RNAs in feedforward loops can help shape the steady-state levels and dynamics of gene expression.
细菌通过一种被称为分解代谢物阻遏的调节机制，有选择性地消耗某些碳源而不是其他碳源。在这里，我们表明，碱基配对 RNA Spot 42 通过直接抑制参与中心和次级代谢、氧化还原平衡以及多种非首选碳源消耗的基因，在大肠杆菌的分解代谢物阻遏中发挥广泛作用。Spot 42 抑制的许多基因受全局调节剂 CRP 的转录激活。由于 CRP 抑制 Spot 42，这些调节剂参与了一个称为多输出前馈环的特定调节回路。我们发现，在存在葡萄糖的情况下，该回路可以减少目标基因的漏表达，并可以在营养条件变化时维持对目标基因的抑制。我们的结果表明，前馈环中的碱基配对 RNA 可以帮助塑造基因表达的稳态水平和动力学。
