Regulation of Antimycin Biosynthesis Is Controlled by the ClpXP Protease
Regulation of Antimycin Biosynthesis Is Controlled by the ClpXP Protease
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DOI：
10.1128/msphere.00144-20
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发表时间：
2020-03-01
期刊：
影响因子：
4.8
通讯作者：
Seipke, Ryan F.
中科院分区：
文献类型：
--
作者：
Bilyk, Bohdan;Kim, Sora;Seipke, Ryan F.
任何微生物的生存都取决于它对环境变化的反应能力。使用胞外胞质功能(ECF)RNA聚合酶西格玛(Sigma)因子是实现对细胞外信号的动态反应的主要策略。链霉菌含有大量的ECF sigma因子，几乎所有的ECF sigma因子都是未知的，但那些已被鉴定的因子通常调节形态分化和/或对环境胁迫反应所需的基因，除了sigma(Anta)，它调节抗癌化合物抗癌药物生产中的起始单位生物合成。与典型的ECF西格玛因子不同，西格玛因子的活性受到同源抗西格玛因子的调节，西格玛因子(ANTA)是一个孤儿，这引发了如何控制其活性的有趣问题。在这里，我们在体外重组了Sigma的ClpXP蛋白分解(ANTA)，但不是缺少C-末端二丙氨酸基序的变体。此外，我们还发现，通过去除ClpXP识别序列，体内Sigma(ANTA)的丰度增加，当细胞ClpXP蛋白酶活性被取消时，蛋白质水平上升。这些数据建立了直接蛋白分解作为ECF RNA聚合酶西格玛因子的替代和到目前为止唯一的控制策略，并扩大了对微生物信号转导调节的聚合理解。重要的是链霉菌产生的天然产物支撑着许多工业和医学上重要的化合物。然而，一个普通物种所拥有的30条类似的生物合成途径中的大多数都没有在实验室中表达。这种未被揭示的生物化学多样性被认为是天然产物药物发现的未开发资源。阻碍开发未表达的生物合成途径的主要障碍是缺乏对其调控的洞察，以及激活其表达的有限技术。我们的发现表明，作为抗霉素生物合成的簇状调节因子，Sigma(Anta)的丰度受ClpXP蛋白酶的控制。据我们所知，这些数据首次将蛋白质降解与天然产物生物合成的调节联系起来，我们预计这将成为放线菌调节其天然产物生产的主要策略。对这一过程的进一步研究将促进对次生代谢表达如何调控的理解，并将有助于激活未表达的生物合成途径。
The survival of any microbe relies on its ability to respond to environmental change. Use of extracytoplasmic function (ECF) RNA polymerase sigma (sigma) factors is a major strategy enabling dynamic responses to extracellular signals. Streptomyces species harbor a large number of ECF sigma factors, nearly all of which are uncharacterized, but those that have been characterized generally regulate genes required for morphological differentiation and/or response to environmental stress, except for sigma(AntA), which regulates starter-unit biosynthesis in the production of antimycin, an anticancer compound. Unlike a canonical ECF sigma factor, whose activity is regulated by a cognate anti-sigma factor, sigma(AntA) is an orphan, raising intriguing questions about how its activity may be controlled. Here, we reconstituted in vitro ClpXP proteolysis of sigma(AntA) but not of a variant lacking a C-terminal di-alanine motif. Furthermore, we show that the abundance of sigma(AntA) in vivo was enhanced by removal of the ClpXP recognition sequence and that levels of the protein rose when cellular ClpXP protease activity was abolished. These data establish direct proteolysis as an alternative and, thus far, unique control strategy for an ECF RNA polymerase sigma factor and expands the paradigmatic understanding of microbial signal transduction regulation.IMPORTANCE Natural products produced by Streptomyces species underpin many industrially and medically important compounds. However, the majority of the similar to 30 biosynthetic pathways harbored by an average species are not expressed in the laboratory. This unrevealed biochemical diversity is believed to comprise an untapped resource for natural product drug discovery. Major roadblocks preventing the exploitation of unexpressed biosynthetic pathways are a lack of insight into their regulation and limited technology for activating their expression. Our findings reveal that the abundance of sigma(AntA), which is the cluster-situated regulator of antimycin biosynthesis, is controlled by the ClpXP protease. These data link proteolysis to the regulation of natural product biosynthesis for the first time to our knowledge, and we anticipate that this will emerge as a major strategy by which actinobacteria regulate production of their natural products. Further study of this process will advance understanding of how expression of secondary metabolism is controlled and will aid pursuit of activating unexpressed biosynthetic pathways.