Understanding and manipulating a conserved and essential transcription factor to activate antibiotic production in Streptomyces species

了解和操纵保守且必需的转录因子以激活链霉菌物种中的抗生素生产

• 批准号: BB/P005292/1
• 负责人: Matthew Hutchings
• 金额: $ 51.77万
• 依托单位: University of East Anglia
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FP005292%2F1
• 关键词: Understanding; manipulating; conserved; essential; transcription

Almost all the antibiotics used in human medicine were discovered >50 years ago and most disease-causing bacteria are now resistant to one or more of these drugs. This means humans are facing a return to the pre-antibiotic era, an alarming situation that has been described as 'antibiotic Armageddon'. The government commissioned O'Neill review on AntiMicrobial Resistance (AMR) estimates that if we do not kick-start antibiotic discovery efforts now then by 2050 drug resistant infections will kill more people than cancer, an estimated 10 million a year. Most of the antibiotics we currently use are natural products derived from the secondary metabolites of soil bacteria and the most important group are called Streptomyces, which make 50% of all known antibiotics. Streptomyces are incredibly important to humans and although scientists have already discovered lots of antibiotics from these bacteria we now know that they only found the really easy to find compounds, the low hanging fruit. Genome sequencing over the last 15 years has revealed that Streptomyces bacteria only make about 25% of their secondary metabolites under laboratory conditions which means that from 1940-60, the so-called golden age of antibiotic discovery, scientists were barely sampling their capability. The rest are called 'silent' secondary metabolites because they do not make them in the lab. The good news is this means we have a big advantage over scientists working in the 20th century - if we can find ways to switch on production of all the silent secondary metabolites in the >600 known species we will find lots of new antibiotics that can enter the clinical trials pipeline. This is the earliest stage in antibiotic discovery and it is vital that we increase our efforts now because it takes 10-15 years to get drugs through clinical trials and approved for use in humans. Probably <1% of antibiotics will be suitable for treating disease so the more natural products we can discover from Streptomyces in the next few decades the better. One way to activate the production of silent secondary metabolites is to understand the natural signals and signalling pathways that control their production in the soil and this is the focus of our research. If we can manipulate those signalling pathways we can force the bacteria to make all of their antibiotics in the laboratory. Ideally we want to identify signalling pathways which effect antibiotic production in all 600+ known Streptomyces species and this is the subject of our proposal. We have identified a signalling pathway consisting of two proteins called MtrA and MtrB and found this is the only conserved and essential pathway in the genus Streptomyces. This means this MtrAB two-component system is found in every single sequenced Streptomyces strain! MtrA is a DNA binding protein and its activity is controlled by the signal sensing protein MtrB. If we disrupt the pathway by deleting the mtrA gene it is lethal. If we delete the mtrB gene it removes the need for an environmental signal to activate the pathway and results in over-production of active MtrA protein which switches on production of antibiotics that are usually silent in the wild-type strains. However, simply over-producing MtrA does not work, we HAVE to remove MtrB as well. In this project we will analyse MtrAB in two model species called S. coelicolor and S. venezuelae. We will determine how MtrB controls MtrA activity, why MtrA is active in the absence of MtrB and why and how MtrA activates the production of silent secondary metabolites. We will also try to make gain of function MtrA proteins that are always active and see if we can use them to switch on antibiotic production in our model strains and in two new talented Streptomyces species that we have isolated and genome sequenced. We call them talented because they appear to encode many novel secondary metabolites and MtrA may allow us to discover new antibiotics from these strains.

人类医学中使用的几乎所有抗生素都是在50年前发现的，大多数致病细菌现在对这些药物中的一种或多种具有耐药性。这意味着人类正面临着回到抗生素出现之前的时代，这种令人担忧的情况被称为“抗生素大决战”。政府委托奥尼尔对抗菌素耐药性（AMR）进行的评估估计，如果我们现在不启动抗生素发现工作，那么到2050年，耐药感染导致的死亡人数将超过癌症，估计每年有1000万人。我们目前使用的大多数抗生素都是从土壤细菌的次生代谢物中提取的天然产物，其中最重要的一类是链霉菌，占所有已知抗生素的50%。链霉菌对人类非常重要，尽管科学家们已经从这些细菌中发现了许多抗生素，但我们现在知道他们只发现了真正容易发现的化合物，即低挂的果实。过去15年的基因组测序显示，链霉菌在实验室条件下只能产生约25%的次级代谢物，这意味着从1940年到1960年，即所谓的抗生素发现的黄金时代，科学家们几乎没有对它们的能力进行采样。其余的被称为“沉默的”次级代谢物，因为它们不是在实验室中产生的。好消息是，这意味着我们比在20世纪工作的科学家有一个很大的优势——如果我们能找到方法，在600种已知物种中启动所有沉默的次级代谢物的生产，我们将找到许多新的抗生素，可以进入临床试验的管道。这是抗生素发现的最早阶段，我们现在加大努力是至关重要的，因为药物需要10-15年的时间才能通过临床试验并被批准用于人类。可能只有不到1%的抗生素适合用于治疗疾病，所以在未来几十年里，我们从链霉菌中发现的天然产物越多越好。激活沉默次生代谢物产生的一种方法是了解控制其在土壤中产生的自然信号和信号通路，这是我们研究的重点。如果我们能控制这些信号通路，我们就能迫使细菌在实验室里制造出所有的抗生素。理想情况下，我们希望确定所有600+已知链霉菌物种中影响抗生素生产的信号通路，这是我们提案的主题。我们已经确定了由两种蛋白质MtrA和MtrB组成的信号通路，并发现这是链霉菌属中唯一保守和必需的信号通路。这意味着MtrAB双组分系统存在于每一个序列链霉菌菌株中！MtrA是一种DNA结合蛋白，其活性受信号传感蛋白MtrB控制。如果我们通过删除mtrA基因来破坏这一途径，它是致命的。如果我们删除mtrB基因，它就不需要环境信号来激活该途径，并导致活性MtrA蛋白的过度生产，从而开启抗生素的生产，而在野生型菌株中通常是沉默的。然而，简单地过度生产地铁是行不通的，我们也必须取消地铁。在这个项目中，我们将分析两种模式物种（S. coelicolor和S. venezuela）的MtrAB。我们将确定MtrB如何控制MtrA活性，为什么MtrA在没有MtrB的情况下活跃，以及MtrA为什么以及如何激活沉默的次级代谢物的产生。我们还将尝试获得始终活跃的MtrA蛋白的功能，看看我们是否可以使用它们在我们的模型菌株和两个新的有才能的链霉菌物种中开启抗生素的生产，我们已经分离并进行了基因组测序。我们称它们为天才，因为它们似乎编码了许多新的次级代谢物，MtrA可能使我们从这些菌株中发现新的抗生素。

项目成果

The MtrAB two-component system controls antibiotic production in Streptomyces coelicolor A3(2).

• DOI: 10.1099/mic.0.000524
• 发表时间: 2017-10
• 期刊: Microbiology (Reading, England)
• 作者: Som NF;Heine D;Holmes N;Knowles F;Chandra G;Seipke RF;Hoskisson PA;Wilkinson B;Hutchings MI
• 通讯作者: Hutchings MI

The Conserved Actinobacterial Two-Component System MtrAB Coordinates Chloramphenicol Production with Sporulation in Streptomyces venezuelae NRRL B-65442.

• DOI: 10.3389/fmicb.2017.01145
• 发表时间: 2017
• 期刊: Frontiers in microbiology
• 影响因子: 5.2
• 作者: Som NF;Heine D;Holmes NA;Munnoch JT;Chandra G;Seipke RF;Hoskisson PA;Wilkinson B;Hutchings MI
• 通讯作者: Hutchings MI