Shewanellaoneidensis是最容易理解的模型微生物,用于研究多种细胞色素(细胞)c,以支持其无与伦比的呼吸多功能性。尽管RNA伴侣Hfq与cytoc产生的调节有关,对这种细菌的生物学途径知之甚少。在这项研究中,来自分泌pyomelanin并具有降低的cytoc含量的自发突变体,我们确定Hfq是与S.oneidensis中两种表型关键相关的调节因子。我们发现血红素生物合成和降解的关键基因的表达在低生产和过度生产水平上受到Hfq的差异影响。通过调节血红素水平,Hfq影响cytoc含量。尽管过量的Hfq会导致产生和去除均质酸(HGA)的酶过量产生,pyomelanin的前体,HmgA的活性受损导致HGA的排泄和聚合形成pyomelanin。我们进一步证明Hfq通过降低细胞内铁含量来介导HmgA活性,因为HmgA是铁依赖性酶。总的来说,我们的工作强调了Hfq介导的转录后调控在S.oneidenis生理学中的重要性,揭示了Hfq影响cytoc生物合成和pyomelanin生产的意外机制。在细菌中的重要性,Hfq参与了翻译后对各种生物过程的调节。在美国,Hfq影响细胞c的含量,这是其呼吸多功能性以及在生物能源和生物修复中的潜在应用的基础。在这项研究中,我们发现Hfq差异调节血红素的生物合成和降解,导致cytoc含量改变。过量的Hfq会对HmgA产生合成效应,一种负责形成pyomelanin的酶。总的来说,所提供的数据表明,由Hfq调节的给定细菌中的生物过程是高度复杂的,相当于在多个生理方面之间需要协调,以使细胞能够迅速响应环境变化。
Shewanella oneidensis is the best understood model microorganism for the study of diverse cytochromes (cytos) c that support its unparallel respiratory versatility. Although RNA chaperone Hfq has been implicated in regulation of cyto c production, little is known about the biological pathways that it affects in this bacterium. In this study, from a spontaneous mutant that secretes
pyomelanin and has a lowered cyto c content, we identified Hfq to be the regulator that critically associates with both phenotypes in S. oneidensis. We found that expression of the key genes in biosynthesis and degradation of heme is differentially affected by Hfq at under- and overproduced levels, and through modulating heme levels, Hfq influences the cyto c content. Although Hfq in excess results in overproduction of the enzymes responsible for both generation and removal of homogentisic acid (HGA), the precursor of
pyomelanin, it is compromised activity of HmgA that leads to excretion and polymerization of HGA to form
pyomelanin. We further show that Hfq mediates HmgA activity by lowering intracellular iron content because HmgA is an iron-dependent enzyme. Overall, our work highlights the significance of Hfq-mediated posttranscriptional regulation in the physiology of S. oneidensis, unraveling unexpected mechanisms by which Hfq affects cyto c biosynthesis and
pyomelanin production. IMPORTANCE In bacteria, Hfq has been implicated in regulation of diverse biological processes posttranslationally. In S. oneidensis, Hfq affects the content of cytos c that serve as the basis of its respiratory versatility and potential application in bioenergy and bioremediation. In this study, we found that Hfq differentially regulates heme biosynthesis and degradation, leading to altered cyto c contents. Hfq in excess causes a synthetic effect on HmgA, an enzyme responsible for
pyomelanin formation. Overall, the data presented manifest that the biological processes in a given bacterium regulated by Hfq are highly complex, amounting to required coordination among multiple physiological aspects to allow cells to respond to environmental changes promptly.