Sonnleitner Elisabeth, Bläsi Udo
Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, Center of Molecular Biology, University of Vienna, Vienna, Austria.
PLoS Genet. 2014 Jun 19;10(6):e1004440. doi: 10.1371/journal.pgen.1004440. eCollection 2014 Jun.
Carbon Catabolite repression (CCR) allows a fast adaptation of Bacteria to changing nutrient supplies. The Pseudomonas aeruginosa (PAO1) catabolite repression control protein (Crc) was deemed to act as a translational regulator, repressing functions involved in uptake and utilization of carbon sources. However, Crc of PAO1 was recently shown to be devoid of RNA binding activity. In this study the RNA chaperone Hfq was identified as the principle post-transcriptional regulator of CCR in PAO1. Hfq is shown to bind to A-rich sequences within the ribosome binding site of the model mRNA amiE, and to repress translation in vitro and in vivo. We further report that Crc plays an unknown ancillary role, as full-fledged repression of amiE and other CCR-regulated mRNAs in vivo required its presence. Moreover, we show that the regulatory RNA CrcZ, transcription of which is augmented when CCR is alleviated, binds to Hfq with high affinity. This study on CCR in PAO1 revealed a novel concept for Hfq function, wherein the regulatory RNA CrcZ acts as a decoy to abrogate Hfq-mediated translational repression of catabolic genes and thus highlights the central role of RNA based regulation in CCR of PAO1.
碳分解代谢物阻遏（CCR）使细菌能够快速适应不断变化的营养供应。铜绿假单胞菌（PAO1）的分解代谢物阻遏控制蛋白（Crc）被认为是一种翻译调节因子，可抑制与碳源摄取和利用相关的功能。然而，最近发现PAO1的Crc缺乏RNA结合活性。在本研究中，RNA伴侣Hfq被鉴定为PAO1中CCR的主要转录后调节因子。研究表明，Hfq可与模型mRNA amiE核糖体结合位点内富含A的序列结合，并在体外和体内抑制翻译。我们进一步报道，Crc发挥着未知的辅助作用，因为在体内对amiE和其他CCR调节的mRNA进行全面抑制需要它的存在。此外，我们发现，当CCR缓解时转录增加的调节RNA CrcZ与Hfq具有高亲和力结合。这项关于PAO1中CCR的研究揭示了Hfq功能的一个新概念，即调节RNA CrcZ作为诱饵消除Hfq介导的分解代谢基因的翻译抑制，从而突出了基于RNA的调节在PAO1的CCR中的核心作用。
