Global post-transcriptional regulators in P. aeruginosa

摘要 铜绿假单胞菌是人类重要的条件致病菌。这是导致 囊性纤维化(CF)患者的发病率和死亡率，是医院获得性肺炎和IS的主要原因 尤其是烧伤创面感染的问题。Hfq是一种保守的全球转录后调控因子， 是铜绿假单胞菌致病所必需的。在其他生物中，Hfq最著名的是它能促进 小调控RNA(SRNA)与其目标转录本之间的碱基配对。Hfq促进的相互作用 在sRNA和其信使核糖核酸靶标之间，通常起到抑制靶标翻译的作用，尽管Hfq可以 还会以独立于sRNA的方式抑制翻译。我们在铜绿假单胞菌Hfq联营公司中发现 有数百个转录本，因为它们来自RNA聚合酶。因为转录和翻译是 在细菌中，hfq与这些新生转录本的相互作用可能允许这种rna结合。 蛋白质尽早发挥其对翻译的调节作用。在目标1中，我们建议 确定所有与铜绿假单胞菌Hfq相互作用的sRNA的靶标，并确定这些 SRNA经常与Hfq一起作用于新生转录本。Hfq与新生病毒的相互作用 转录本对如何控制转录本丰度具有重要意义；具体地说，Hfq- 依赖抑制新生转录本的翻译将使它们能够被转录本访问 终止因子Rho或核糖核酸酶。在目标1中，我们将确定Hfq是否会减少 那些它通过影响Rho介导的转录终止或通过效应结合的新生转录本 关于RNA的降解。我们发现铜绿假单胞菌中的第二个全球转录后调控因子称为 RSMA还瞄准了数百份新生的成绩单，其中包括许多被HfQ瞄准的成绩单。RSMA是 铜绿假单胞菌急性和慢性感染表型转换的关键调节因子和目标2 将调查HfQ和RSMA是否通过竞争或合作来调节对方的活动 共同的目标。与Hfq一样，RSMA与目标mRNA物种的结合通常会抑制它们的翻译。在……里面 目的3我们建议确定RSMA与新生转录本的相互作用是否影响它们的 通过影响Rho介导的转录终止或对RNA降解的影响而获得丰度。这个 这项提案中概述的实验有望阐明hfq和rsma如何控制基因表达。 通过他们广泛瞄准新生的成绩单。这些全球转录后基因的共转录活动 转录调控因子的研究还不够深入，我们提议的研究可能不仅会产生影响 Hfq和RSMA如何影响铜绿假单胞菌的毒力，以及它们的同源基因如何影响 毒力基因在含有它们的其他病原菌中的表达。

Abstract Pseudomonas aeruginosa is an important opportunistic pathogen of humans. It is the principal cause of morbidity and mortality in Cystic Fibrosis (CF) patients, a major cause of hospital-acquired pneumonia and is particulary problematic in burn wound infections. Hfq is a conserved global post-transcriptional regulator that is required for the virulence of P. aeruginosa. In other organisms Hfq is best known for its ability to promote the base-pairing between small regulatory RNAs (sRNAs) and their target transcripts. Hfq-promoted interaction between an sRNA and its mRNA target typically functions to repress translation of the target, although Hfq can also inhibit translation in an sRNA-independent fashion. We have found that in P. aeruginosa Hfq associates with hundreds of transcripts as they emerge from RNA polymerase. Because transcription and translation are coupled in bacteria, the interaction of Hfq with these nascent transcripts presumably allows this RNA-binding protein to exert its regulatory effects on translation at the earliest possible opportunity. In Aim 1 we propose to identify the targets of all the sRNAs that interact with Hfq in P. aeruginosa and determine whether these sRNAs frequently work in conjunction with Hfq on nascent transcripts. The interaction of Hfq with nascent transcripts has important implications for how transcript abundance can be controlled; specifically, Hfq- dependent inhibition of the translation of nascent transcripts would render them accessible to the transcription termination factor Rho or to ribonucleases. In Aim 1 we will determine whether Hfq reduces the abundance of those nascent transcripts it binds through effects on Rho-mediated transcription termination or through effects on RNA degradation. We have found that a second global post-transcriptional regulator in P. aeruginosa called RsmA also targets hundreds of nascent transcripts, including many of those that are targeted by Hfq. RsmA is a key regulator of the switch between acute and chronic infection phenotypes in P. aeruginosa and in Aim 2 we will investigate whether Hfq and RsmA modulate each other’s activities through competition or cooperation on common targets. Like Hfq, the binding of RsmA to target mRNA species typically inhibits their translation. In Aim 3 we propose to determine whether the interaction of RsmA with nascent transcripts influences their abundance through effects on Rho-mediated transcription termination or effects on RNA degradation. The experiments outlined in this proposal are expected to illuminate how Hfq and RsmA control gene expression through their widespread targeting of nascent transcripts. The co-transcriptional activities of these global post- transcriptional regulators have been underexplored and our proposed studies may have implications not only for how Hfq and RsmA impact the virulence of P. aeruginosa, but also for how their orthologs influence virulence gene expression in other pathogenic bacteria that contain them.