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，作为关键酶的辅因子。然而，铜也可以对细胞产生毒性作用，并且已经发展了安全处理的机制。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）是在甲烷氧化细菌（甲烷氧化菌）中发现的，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病原体的，因此一种可以通过吸收大量铜离子进行防御的蛋白质的存在可能是毒力的关键。显然需要更好地理解Csps在细菌处理铜中的作用，这将使用一系列体外和体内方法来实现。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的发孢甲基弯菌OB 3b，可以拥有胞质Csp 3和输出Csp 1。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）。这两个CSP来自M.已经在体外表征了丝孢霉OB 3b（Nature 2015，525，140-143; Sci. Rep. 2016，6：39065），并且在Cu（I）如何结合方面显示出惊人的差异（Angew.化学国际编辑英文版2017，56，8697-8700）和Cu（I）去除速率。了解负责这些差异的结构特征和它们对铜的储存和去除的甲烷氧化菌内的影响将进行研究。病原体，如淋病奈瑟氏菌，沙门氏菌肠道SV。鼠伤寒杆菌、铜绿假单胞菌和洋葱伯克霍尔德氏菌复合体可以具有Csp 1或Csp 3。分析这些Csp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。一种吸引人的可能性是比较来自铜绿假单胞菌菌株的Csp 3和来自B的Csp 1。洋葱复合体这两种机会致病菌都可以产生多药耐药性，是囊性纤维化患者的主要问题。了解Csps在这些生物体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剂。

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.