Nothing wasted: Peptidoglycan recycling in mycobacteria

没有浪费：分枝杆菌中肽聚糖的回收

• 批准号: BB/N011945/1
• 负责人: Patrick Moynihan
• 金额: $ 38.28万
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FN011945%2F1
• 关键词: Nothing; wasted; Peptidoglycan; recycling; mycobacteria

Mycobacterium tuberculosis is a living paradox. Amongst bacteria, it possesses one of the single most complex and carbon-rich cell walls and yet it thrives in the decidedly nutrient poor environment of the human lung. This is made even more impressive considering the fact that components of the mycobacterial cell wall are potent triggers of the innate immune system. Therefore, to support stable growth in their host, these bacteria must be exquisitely efficient with their available nutrients and be able to hide themselves from the immune system. The innermost component of the mycobacterial cell wall is a complex macromolecule called peptidoglycan (PG). While textbook illustrations of PG suggest that it is a static bag-like structure, in reality it is a heavily modified and dynamic molecule that prevents the cell from exploding while simultaneously giving it shape. Throughout the life cycle of the bacterium, PG must constantly and carefully be cut and remodeled to support growth and division. Researchers have long studied PG, chiefly because of its essential nature. Indeed, the first clinical antibiotic, penicillin, specifically targets the biosynthesis of PG. While much of this biosynthesis has been understood for many years, relatively little is known about what happens to PG after it is built. This is even truer for the PG of M. tuberculosis, which is a global pathogen and the second leading killer of people amongst infectious diseases. For example, nothing is known about the fate of mycobacterial PG fragments once lytic enzymes have cut them from the cell wall. This is an important question because as mentioned above, these PG fragments are potent stimulators of the immune system and command a great deal of scarce resources to make. Intriguingly, these same PG fragments are capable of triggering resuscitation of the bacterium from the dormant phase of its lifestyle. Dormant M. tuberculosis is capable of persisting undetected for years inside of its host before producing an active infection. This severely complicates control of the disease and associated outbreaks, because even if they are detected, dormant M. tuberculosis are exceptionally antibiotic resistant. These points make it clear that an understanding of the fate of M. tuberculosis cell wall fragments is needed. In some bacteria complex PG recycling systems have been described which work by bringing PG fragments back into the cell to be reused. In all cases observed to-date this recycling system is important to the ability of the bacterium to infect its host. Despite this, PG recycling has never been investigated in M. tuberculosis. It is important that this pathway be investigated because it is very likely that the elements of a mycobacterial PG recycling system are novel antibiotic targets. During this Fellowship I will use new and exciting techniques to demonstrate that mycobacteria recycle their PG. I will take a high-resolution approach by exploring the precise structure of the PG fragments that are being recycled. I will then determine the cellular machinery that is required for PG recycling and characterise the key proteins involved in the pathway. Finally, I will examine the relationship between tuberculosis resuscitation and PG recycling. This work will address the M. tuberculosis paradox and show how it is able to balance its nutritional and growth requirements with its nutrient poor environment and the need to hide itself from our immune system.

结核分枝杆菌是一个活生生的悖论。在细菌中，它拥有最复杂和最富碳的细胞壁之一，但它在人类肺部营养贫乏的环境中茁壮成长。考虑到分枝杆菌细胞壁的成分是先天免疫系统的有效触发剂，这一点更加令人印象深刻。因此，为了支持它们在宿主中的稳定生长，这些细菌必须对它们的可用营养物非常有效，并且能够隐藏自己免受免疫系统的攻击。分枝杆菌细胞壁的最内层成分是一种称为肽聚糖（PG）的复杂大分子。虽然PG的教科书插图表明它是一种静态的袋状结构，但实际上它是一种经过大量修改的动态分子，可以防止细胞爆炸，同时赋予其形状。在细菌的整个生命周期中，PG必须不断地被小心地切割和重塑，以支持生长和分裂。研究人员长期以来一直在研究PG，主要是因为它的本质。事实上，第一种临床抗生素青霉素专门针对PG的生物合成。虽然多年来人们已经了解了这种生物合成的大部分内容，但对PG在构建后发生的情况知之甚少。这对M的PG来说更是如此。结核病是一种全球性病原体，也是传染病中第二大杀手。例如，当裂解酶将分枝杆菌PG片段从细胞壁上切下后，它们的命运就无从知晓了。这是一个重要的问题，因为如上所述，这些PG片段是免疫系统的有效刺激物，并且需要大量稀缺资源来制造。有趣的是，这些相同的PG片段能够触发细菌从其生活方式的休眠阶段复苏。多罗米结核病能够在宿主体内持续数年而不被发现，然后才产生活动性感染。这严重地使控制疾病和相关的爆发复杂化，因为即使它们被检测到，休眠的M。结核病对抗生素的耐药性非常强。这几点说明，要了解M.需要结核细胞壁碎片。在一些细菌中，已经描述了复杂的PG再循环系统，其通过将PG片段带回细胞以重新使用来工作。在迄今为止观察到的所有情况下，这种循环系统对细菌感染其宿主的能力都很重要。尽管如此，PG回收从未在M进行过调查。结核重要的是，这一途径进行调查，因为它是非常有可能的分枝杆菌PG回收系统的元素是新的抗生素的目标。在这个奖学金期间，我将使用新的和令人兴奋的技术来证明分枝杆菌回收他们的PG。我将采取高分辨率的方法，探索被回收的PG片段的精确结构。然后，我将确定PG回收所需的细胞机制，并确定参与该途径的关键蛋白质。最后，我将研究结核复苏和PG循环之间的关系。这项工作将解决M。结核病悖论，并显示它是如何能够平衡其营养和生长的需求与营养不良的环境，并需要隐藏自己从我们的免疫系统。

项目成果

Inhibiting mycobacterial tryptophan synthase by targeting the inter-subunit interface.

通过靶向亚基界界面来抑制分枝杆菌色氨酸合酶。

• DOI: 10.1038/s41598-017-09642-y
• 发表时间: 2017-08-25
• 期刊: Scientific reports
• 影响因子: 4.6
• 作者: Abrahams KA;Cox JAG;Fütterer K;Rullas J;Ortega-Muro F;Loman NJ;Moynihan PJ;Pérez-Herrán E;Jiménez E;Esquivias J;Barros D;Ballell L;Alemparte C;Besra GS
• 通讯作者: Besra GS

In vitro characterization of the antivirulence target of Gram-positive pathogens, peptidoglycan O-acetyltransferase A (OatA).

• DOI: 10.1371/journal.ppat.1006667
• 发表时间: 2017-10
• 期刊: PLoS pathogens
• 影响因子: 6.7
• 作者: Sychantha D;Jones CS;Little DJ;Moynihan PJ;Robinson H;Galley NF;Roper DI;Dowson CG;Howell PL;Clarke AJ
• 通讯作者: Clarke AJ

Two Faces of CwlM, an Essential PknB Substrate, in Mycobacterium tuberculosis.

• DOI: 10.1016/j.celrep.2018.09.004
• 发表时间: 2018-10-02
• 期刊: Cell reports
• 影响因子: 8.8
• 作者: Turapov O;Forti F;Kadhim B;Ghisotti D;Sassine J;Straatman-Iwanowska A;Bottrill AR;Moynihan PJ;Wallis R;Barthe P;Cohen-Gonsaud M;Ajuh P;Vollmer W;Mukamolova GV
• 通讯作者: Mukamolova GV

Photoactivable Glycolipid Antigens Generate Stable Conjugates with CD1d for Invariant Natural Killer T Cell Activation.

• DOI: 10.1021/acs.bioconjchem.8b00484
• 发表时间: 2018-09-19
• 期刊: Bioconjugate chemistry
• 影响因子: 4.7
• 作者: Veerapen N;Kharkwal SS;Jervis P;Bhowruth V;Besra AK;North SJ;Haslam SM;Dell A;Hobrath J;Quaid PJ;Moynihan PJ;Cox LR;Kharkwal H;Zauderer M;Besra GS;Porcelli SA
• 通讯作者: Porcelli SA

The lasting impact of the 2013 Beveridge poster award.

2013 年贝弗里奇海报奖的持久影响。

• DOI: 10.1139/cjm-2017-0458
• 发表时间: 2018
• 期刊: Canadian journal of microbiology
• 影响因子: 2.8
• 作者: Moynihan PJ