Post-translation regulation of antibiotic production in Streptomyces: the loaded gun hypothesis.

链霉菌抗生素生产的翻译后调控：装弹枪假说。

• 批准号: BB/W000628/1
• 负责人: Matthew Hutchings
• 金额: $ 70.67万
• 依托单位: John Innes Centre
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FW000628%2F1
• 关键词: Post; translation; regulation; antibiotic; production

Around three quarters of the antibiotics we use in human medicine are derived from the natural products of soil bacteria and fungi. We call these natural products specialised metabolites because they have a specialised function, which is usually to kill other bacteria and fungi in the highly competitive soil environment. These molecules can also be toxic to worms, insects and even plants and many have been used in medicine to treat parasite infections and as herbicides or pesticides in agriculture. The biggest producers of specialised metabolites are Streptomyces bacteria which make around 50% of all known antibiotics. These bacteria are incredibly important to humans but we have relatively little understanding of how they control the production of their specialised metabolites. This is important because they only make around 10% of their specialised metabolites when we grow them in the laboratory. We know this from sequencing all the DNA in their cells which shows they have the instructions and capacity to make many more. If we can understand how they control their production we should be able to engineer strains to switch on production of all the specialised metabolites in all of the >600 known Streptomyces species and discover many new and potentially useful natural products, including antibiotics. As part of our efforts to identify the master regulators of antibiotic production, we characterised a DNA binding protein called MtrA which is found in all Streptomyces species. MtrA controls antibiotic production in all the Streptomyces strains that have been tested so far and is part of a signal transduction pathway called a two-component system. These signalling systems are common in bacteria. MtrA is a response regulator, and these proteins are typically transcription factors which control gene expression by binding to promoter DNA. The DNA binding activity of MtrA is controlled by MtrB, a sensor kinase which spans the cell membrane and senses a signal outside the cell and then phosphorylates and activates MtrA inside the cell. MtrA binds to around 80% of the predicted biosynthetic gene clusters for specialised metabolites in Streptomyces coelicolor and S. venezuelae. MtrA also binds to other transcription factors which is unusual in bacteria and to enzymes involved in making specialised metabolites which, to our knowledge, has never been described before for any other bacterial transcription factor. In this proposal we will use S. venezuelae as a model to characterise the regulation of antibiotic production by MtrA since it controls chloramphenicol production by binding to the transporter genes and to the enzyme CmlS, which catalyses the final step in the biosynthetic pathway. It appears that antibiotic biosynthesis does not occur from scratch. Instead we hypothesise that it is like a loaded gun, the precursor is made but the final step is blocked by MtrA. When MtrA is switched off it is like pulling the trigger - the final step occurs, and the active antibiotic is made, the transport genes are expressed and the active compound is exported from the cell. In this project we will test this "loaded gun" hypothesis and the results will likely change the way we think about bacterial transcription factors and the regulation of antibiotic biosynthesis.MtrA also binds to a closely related response regulator called Vnz13500 which is conserved in Streptomyces species and probably also activated by MtrB suggesting its functions are complex in S. venezuelae. To test whether these functions are conserved in other streptomycetes we will use the distantly related S. coelicolor which is also experimentally tractable. Published data from our and other groups suggests S. coelicolor MtrAB and SCO3008 (its Vnz13500 homologue) are involved in controlling production of its antibiotic undecylprodigiosin and we will test if it does this at both the transcriptional and post translational levels.

我们在人类医学中使用的大约四分之三的抗生素来自土壤细菌和真菌的天然产物。我们称这些天然产品为特殊代谢物，因为它们具有特殊的功能，通常是在竞争激烈的土壤环境中杀死其他细菌和真菌。这些分子对蠕虫、昆虫甚至植物也有毒性，许多分子已被用于治疗寄生虫感染的药物，并在农业中用作除草剂或杀虫剂。专业代谢物的最大生产者是链霉菌，它制造了所有已知抗生素的50%左右。这些细菌对人类非常重要，但我们对它们如何控制其专业代谢物的产生知之甚少。这一点很重要，因为当我们在实验室培养它们时，它们只产生大约10%的专业代谢物。我们从对它们细胞中所有DNA的测序中得知这一点，这表明它们有指令和能力制造更多的DNA。如果我们能够了解它们是如何控制自己的生产的，我们应该能够设计菌株，使其能够在所有已知的&gt；600种链霉菌中产生所有特定代谢物，并发现许多新的、潜在有用的天然产品，包括抗生素。作为我们识别抗生素生产的主要调节者的努力的一部分，我们鉴定了一种名为MTRA的DNA结合蛋白，它在所有链霉菌中都存在。MTRA控制着到目前为止已经测试过的所有链霉菌菌株的抗生素生产，是称为双组分系统的信号转导途径的一部分。这些信号系统在细菌中很常见。MTRA是一种反应调节因子，这些蛋白是典型的转录因子，通过与启动子DNA结合来控制基因的表达。MTRA的DNA结合活性由mtrB控制，mtrB是一种跨越细胞膜的传感器激酶，它感知细胞外的信号，然后磷酸化并激活细胞内的MTRA。MTRA与天蓝色链霉菌和金黄色链霉菌专门化代谢物的预测生物合成基因簇中的大约80%结合。MTRA还与其他转录因子结合，这在细菌中是不寻常的，并与参与制造专门代谢物的酶结合，据我们所知，以前从未对任何其他细菌转录因子进行过描述。在本提案中，我们将使用S.venezuelae作为一个模型来表征MTRA对抗生素生产的调节，因为它通过与转运蛋白基因和催化生物合成途径的最后一步的酶CMLS结合来控制氯霉素的生产。似乎抗生素的生物合成不是从头开始的。相反，我们假设它就像一把上了膛的枪，先导已经完成，但最后一步被MTRA阻止。当MTRA被关闭时，就像扣动扳机--最后一步发生了，活性抗生素被制造出来，转运基因被表达，活性化合物被从细胞中输出。在这个项目中，我们将测试这个“上膛的枪”假说，结果可能会改变我们对细菌转录因子和抗生素生物合成调控的看法。MtrA还与一个密切相关的反应调节因子Vnz13500结合，该调节因子在链霉菌中是保守的，可能也被MtrB激活，这表明它在S.venezuelae中的功能是复杂的。为了测试这些功能在其他链霉菌中是否保守，我们将使用远缘关系的天蓝色链霉菌，它在实验上也很容易驯化。我们和其他团队发表的数据表明，天蓝色S.coelicolor MtrAB和SCO3008(其Vnz13500同源物)参与控制其抗生素十一烷基灵芝蛋白的生产，我们将测试它是否在转录和翻译后水平上做到这一点。

项目成果

Evidence of a role for CutRS and actinorhodin in the secretion stress response in Streptomyces coelicolor M145.

• DOI: 10.1099/mic.0.001358
• 发表时间: 2023-07
• 期刊: MICROBIOLOGY-SGM
• 影响因子: 2.8
• 作者: McLean, Thomas C.;Beaton, Ainsley D. M.;Martins, Carlo;Saalbach, Gerhard;Chandra, Govind;Wilkinson, Barrie;Hutchings, Matthew I.
• 通讯作者: Hutchings, Matthew I.