Faigenbaum-Romm Raya, Reich Avichai, Gatt Yair E, Barsheshet Meshi, Argaman Liron, Margalit Hanah
Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel.
Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel.
Cell Rep. 2020 Mar 3;30(9):3127-3138.e6. doi: 10.1016/j.celrep.2020.02.016.
Bacterial small RNAs (sRNAs) are posttranscriptional regulators of gene expression that base pair with complementary sequences on target mRNAs, often in association with the chaperone Hfq. Here, using experimentally identified sRNA-target pairs, along with gene expression measurements, we assess basic principles of regulation by sRNAs. We show that the sRNA sequence dictates the target repertoire, as point mutations in the sRNA shift the target set correspondingly. We distinguish two subsets of targets: targets showing changes in expression levels under overexpression of their sRNA regulator and unaffected targets that interact more sporadically with the sRNA. These differences among targets are associated with their Hfq occupancy, rather than with the sRNA-target base-pairing potential. Our results suggest that competition among targets over Hfq binding plays a major role in the regulatory outcome, possibly awarding targets with higher Hfq binding efficiency an advantage in the competition over binding to the sRNA.
细菌小RNA（sRNA）是基因表达的转录后调节因子，它们与靶mRNA上的互补序列进行碱基配对，通常与伴侣蛋白Hfq结合。在这里，我们利用实验确定的sRNA-靶标对以及基因表达测量结果，评估sRNA的基本调控原理。我们发现，sRNA序列决定了靶标库，因为sRNA中的点突变会相应地改变靶标集。我们区分了两个靶标子集：在其sRNA调节因子过表达时表达水平发生变化的靶标，以及与sRNA相互作用更分散的未受影响的靶标。这些靶标之间的差异与它们的Hfq占有率有关，而不是与sRNA-靶标碱基配对潜力有关。我们的结果表明，靶标之间对Hfq结合的竞争在调控结果中起主要作用，可能会使具有更高Hfq结合效率的靶标在与sRNA结合的竞争中具有优势。
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