Studying the structure and function of a novel family of bacterial copper storage proteins

铜是大多数生物体必需的金属离子，是关键酶的辅助因子。然而，铜也会对细胞产生毒性作用，并且已经形成了安全处理铜的机制。我们发现了一个新的蛋白质家族，可以让细菌安全地储存铜（Nature 2015, 525, 140-143）。这些蛋白质（Csps）在甲烷氧化细菌（甲烷氧化菌）中被发现，它们为氧化甲烷（一种强效温室气体）的主要酶储存铜。Csp同源物广泛存在于甲烷氧化菌和一系列其他细菌中，包括重要的病原体。由于铜被认为是宿主用来攻击入侵的病原体的，一种蛋白质的存在可以通过吸收大量的铜离子来进行防御，这可能是毒性的关键。显然需要更好地了解Csps在细菌处理铜中的作用，这将通过一系列体外和体内方法实现。这项工作可以在甲烷氧化菌、病原体或广泛使用的模式生物枯草芽孢杆菌中进行。甲烷氧化菌，如最初发现csp的Methylosinus trichosporium OB3b，可以拥有胞浆Csp3和输出Csp1。后者已被证明为几乎无处不在的膜结合颗粒甲烷单加氧酶（pMMO）储存Cu(I)。这两种来自M. trichosporium OB3b的Csps已经在体外进行了表征(Nature 2015, 525,140 -143; Sci。rep 2016, 6:39 9065)，并且在Cu(I)的结合方式方面显示出惊人的差异(Angew。化学。Int。环境科学与技术，2017,35(6):693 - 697。将研究导致这些差异的结构特征及其对甲烷化菌中铜的储存和去除的影响。淋病奈瑟菌、肠炎沙门氏菌等病原体。鼠伤寒菌、铜绿假单胞菌和洋葱伯克霍尔德菌复合体可以拥有Csp1或Csp3。分析这些Csps的体外特性及其在致病性中的潜在作用是可以进行研究的另一个领域。比较铜绿假单胞菌菌株的Csp3s和洋葱芽孢杆菌复合体的Csp1s是一种很有吸引力的可能性。这两种机会性病原体都可产生多重耐药性，是囊性纤维化患者的主要关注点。了解Csps在这些生物中的作用及其对发病机制的潜在影响有助于开发新的抗菌素。

Copper is an essential metal ion for most organisms, acting as a cofactor for key enzymes. However, copper can also have toxic effects on cells, and mechanisms have evolved for its safe handling. We have discovered a new family of proteins that allow bacteria to safely store copper (Nature 2015, 525, 140-143). These proteins (the Csps) were identified in methane-oxidising bacteria (methanotrophs), where they store copper for the main enzyme that oxidises methane, a potent greenhouse gas. Csp homologues are widespread in methanotrophs and a range of other bacteria, including important pathogens. As copper is thought to be used by hosts to attack invading pathogens, the presence of a protein that can defend by soaking up large quantities of copper ions could be key for virulence. A better understanding of the role of Csps in copper handling by bacteria is clearly required, which will be achieve using a range of in vitro and in vivo approaches. This work can be carried out in methanotrophs, pathogens, or the widely used model organism Bacillus subtilis. Methanotrophs, such as Methylosinus trichosporium OB3b in which the Csps were originally discovered, can possess a cytosolic Csp3 and an exported Csp1. The latter has been shown to store Cu(I) for the almost ubiquitous membrane-bound particulate methane monooxygenase (pMMO). Both of these Csps from M. trichosporium OB3b have been characterised in vitro (Nature 2015, 525, 140-143; Sci. Rep. 2016, 6:39065) and display striking differences in terms of how Cu(I) binds (Angew. Chem. Int. Ed. Engl. 2017, 56, 8697-8700) and the rate of Cu(I) removal. Understanding the structural features that are responsible for these differences and their influence on copper storage and removal within the methanotroph will be studied.Pathogens such as Neisseria gonorrhoeae, Salmonella enterica sv. Typhimurium, Pseudomonas aeruginosa, and the Burkholderia cepacia complex can possess either a Csp1 or Csp3. Analysing the in vitro properties of these Csps and their potential role in pathogenicity is another area in which studies can be undertaken. An appealing possibility is to compare Csp3s from P. aeruginosa strains and Csp1s from the B. cepacia complex. Both of these opportunistic pathogens can develop multi-drug resistance and are a major concern for patients with cystic fibrosis. Understanding the role of the Csps in these organisms and their potential influence on pathogenesis could help in developing new antimicrobials.