转铜伴侣的功能与结构特性

铜是生物体不可缺少的一种元素,在细胞内把铜转运到含铜的蛋白质是细胞正常代谢的基本要求,转铜伴铝在体内执行重要的生理功能,它们不但保护细胞免受游离铜离子的有害作用。而且也确保铜被运输到其特异的靶蛋白。作者综述了转铜伴铝的功能、结构特性,以及可能的金属转移机制。     

Cu+的转运体系

铜是生物体内必需的营养元素,参与体内许多生化反应。细胞膜上的蛋白质和细胞质内可溶性多肤(即分子伴侣)参与了铜离子的跨越细胞膜的转运和细胞内的定位。铜离子被CTR系统转运进入细胞后,主要有三类分子伴侣——ATxl、Coxl7、LYS7介导铜离子在细胞内的运输与定位。每一种分子伴侣都特异性地识别靶分子。细胞膜上和细胞质内的转运体系发生突变,将会诱发很多疾病。近年来,随着对某些疾病机理的深入揭示,人们越来越重视对铜离子异常代谢所引起的疾病的研究。     

酵母和植物中铜的转运系统及其调控

铜是生物正常生命活动所必需的微量矿质元素。酵母和植物中有复杂的机制来调节铜的摄取、分布、螯合以及输出。本文集中讨论了酵母和植物中铜离子的转运体、铜的金属伴侣及其基因转录水平的调控。     

酵母和植物中铜的转运系统及其调控

铜是生物正常生命活动所必需的微量矿质元素。酵母和植物中有复杂的机制来调节铜的摄取、分布、螯合以及输出。本文集中讨论了酵母和植物中铜离子的转运体、铜的金属伴侣及其基因转录水平的调控。     

真菌铜离子内稳态（homeostasis）调节的多样性

摘要：铜是生物体中必需的微量元素之一,作为多种氧化酶的辅助因子参与不同的生物反应,对于维持生命活动起到重要的作用。但在过量的情况下,无论是一价铜离子还是二价铜离子对于生物体都具有很强的细胞毒性,因此铜的代谢是受细胞严格调控的。以酿酒酵母(Saccharomyces cerevisiae)为模式生物对铜代谢的研究已取得了很大进展,对其它高等生物体内铜代谢及其重要生理功能提供了重要信息。本文对酿酒酵母中铜离子的吸收、转运以及在细胞内的代谢调控的新进展进行了归纳,并结合自己的研究综述了真菌铜代谢调节的共性与差异。     

维持细胞内铜离子浓度稳定的分子机制

对生命而言,铜是一种必须的微量元素,它以辅基的形式参与细胞内多种重要的代谢途径。赖氨酸氧化酶参与结缔组织的形成和胶原交联,超氧化物歧化酶清除胞内自由基,细胞色素氧化酶是呼吸链电子传送蛋白,酷氨酸酶参与色素形成途径,多巴胺β羟化酶则与神经传导有关。细胞内铜离子浓度过低会影响这些酶的活性及相应的生理代谢途径,影响细胞的生存。但细胞内铜离子浓度超过生理需求也会引起严重的问题。铜离子能氧化蛋白,脂类和ＤＮ     

铜离子影响谷氨酰胺发酵的研究

研究了铜离子对谷氨酰胺发酵的影响,结果表明,微量铜离子对生成谷氨酰胺有促进作用,高浓度铜离子对微生物细胞有毒害作用。     

集胞藻PCC6803铜离子诱导表达平台的构建

在集胞藻PCC6803中,基因敲除是研究基因功能的最直接有效的方法,但是对于某些生存必需的基因则无法通过这种方法获得突变株。为研究集胞藻PCC6803中此类基因的功能,在其基因组中构建了一个petE基因启动子（PpetE）控制的铜离子诱导表达的平台。将集胞藻PpetE装配在lacZ报告基因的上游,通过同源双交换整合到这种蓝藻的基因组中。通过调节培养基中铜离子的浓度发现,lacZ的表达能够人为控制。特别是当铜离子浓度在6－400nmoL／L范围时,LacZ活力随铜离子浓度增加呈S型增长关系。利用这个铜离子诱导表达平台,可以控制某些必需基因的表达：提供铜离子维持细胞生存;而撤去铜离子时则关闭基因的表达,可以观察其对生命活动的影响。     

模式生物斑马鱼在微量元素代谢研究中的应用

微量元素如铁、锌、铜等对维持生物体代谢和健康至关重要,其含量失衡会造成代谢异常甚至死亡,因此生物体存在复杂机制维持这些微量元素的稳态代谢平衡（homeostasis）。近年来国际上一些实验室尝试用模式脊椎生物斑马鱼来开展该领域的研究,展示出斑马鱼的特有优势。特别是大规模正向遗传学筛选的成功开展,一系列微量元素代谢异常的突变体（如：weissherbst、chardonnay、chianti、shiraz、gavi、calamity和catastrophe）相继发现,为研究离子代谢调控机制和相关疾病的发病机理,提供了整体动态的活体模型。铁代谢相关基因加,2J和grx5都己在斑马鱼中成功定位克隆,斑马鱼铜载体基因atp7a突变体calamity的深入研究,进一步阐明了Menkes病的发病机理。利用斑马鱼的优势,结合小鼠模型和人群来研究微量元素的体内稳态代谢平衡将是微量元素代谢机制研究的新方向。     

维持细胞内铜离子浓度稳定的分子机制

对生命而言,铜是一种必须的微量元素,它以辅基的形式参与细胞内多种重要的代谢途径。赖氨酸氧化酶参与结缔组织的形成和胶原交联,超氧化物歧化酶清除胞内自由基,细胞色素氧化酶是呼吸链电子传送蛋白,酪氨酸酶参与色素形成途径,多巴胺β羟化酶则与神经传导有关。细胞内铜离子浓度过低会影响这些酶的活性及相应的生理代谢途径,影响细胞的生存。但细胞内铜离子浓度超过生理需求也会引起严重的问题。铜离子能氧化蛋白,脂类和ＤＮＡ,同时促进形成自由基,引起细胞死亡［１］。人体很多疾病都是由于铜离子代谢异常引起的,其中最著名的就是Ｗｉｌｓｏｎ［２］ 和Ｍｅｎｋｓ［３］病,它们分别是由过多铜离子在细胞内堆积和细胞内铜离子浓度过低导致的。另外,铜离子缺乏还会引起心脏疾病［４］。所以,将细胞内铜离子浓度维持在一稳定水平对细胞生存至关重要。生理性铜离子浓度的维持主要在于四个环节：铜离子进入胞内（ｕｐｔａｋｅ）、胞内运送（ｔｒａｎｓｌｏｃａｔｉｏｎ）、合成金属蛋白（ｓｙｎｔｈｅｓｉｓ）及清除过多铜离子（ｅｌｉｍ ｉｎａｔｉｏｎ）［５］。对于过高或过低的铜离子浓度,细胞主要是通过改变流入量（ｉｎｆｌｕｘ）和流出量（ｅｆｆｌｕｘ）来应答。另外,金属硫蛋白可与过多铜离子结合,避免其破坏作用,这种保护方式叫隔离（ｓｅｑｕｅｓｔｒａｔｉｏｎ）。事实上,每一环节都有不止一种蛋白和调控蛋白在起作用。近年来对这方面的研究取得了不少进展,本文在此对细菌、酵母和人的铜离子代谢途径做一总结和比较。     

拟南芥COPT家族蛋白研究进展

铜(Cu)是植物必需的微量元素, 作为多种酶的辅因子参与许多植物生理生化反应。Cu缺乏和过量均影响植物正常生长发育, 因此植物进化出精妙复杂的调控网络来严格控制植物体内的Cu含量。植物Cu转运蛋白COPT家族成员与Cu有很高的亲和力, 能够调节植物对Cu的吸收和转运, 在维持植物体内Cu稳态平衡过程中发挥重要作用。COPT蛋白涉及不同的Cu转运功能, 如从外界环境中摄取Cu、从细胞器中输出Cu、长距离运输Cu以及在不同器官间动用和再分配Cu。此外, COPT蛋白在其它离子的稳态平衡维持、昼夜节律性生物钟调控、植物激素合成和植物对激素信号的感受过程中也发挥重要作用。该文综述了模式植物拟南芥(Arabidopsis thaliana) COPT家族各成员的表达和定位、调控机制以及生物学功能等方面的最新进展。     

拟南芥COPT家族蛋白研究进展

铜(Cu)是植物必需的微量元素, 作为多种酶的辅因子参与许多植物生理生化反应。Cu缺乏和过量均影响植物正常生长发育, 因此植物进化出精妙复杂的调控网络来严格控制植物体内的Cu含量。植物Cu转运蛋白COPT家族成员与Cu有很高的亲和力, 能够调节植物对Cu的吸收和转运, 在维持植物体内Cu稳态平衡过程中发挥重要作用。COPT蛋白涉及不同的Cu转运功能, 如从外界环境中摄取Cu、从细胞器中输出Cu、长距离运输Cu以及在不同器官间动用和再分配Cu。此外, COPT蛋白在其它离子的稳态平衡维持、昼夜节律性生物钟调控、植物激素合成和植物对激素信号的感受过程中也发挥重要作用。该文综述了模式植物拟南芥(Arabidopsis thaliana) COPT家族各成员的表达和定位、调控机制以及生物学功能等方面的最新进展。     

Ligand reaction-based fluorescent peptide probes for the detection of Cu2+ and glutathione

Copper is a critical element in both human and animal metabolic processes. Its role includes supporting connective tissue cross-linking, as well as iron and lipid metabolism; at the same time, copper is also a toxic heavy metal that can cause harm to both the environment and human health. Glutathione (GSH) is a tripeptide composed of glutamic acid, cysteine, and glycine combined with sulfhydryl groups. Its properties include acting as an antioxidant and facilitating integrative detoxification. GSH is present in both plant and animal cells and has a fundamental role in maintaining living organisms. GSH is the most abundant thiol antioxidant in the human body. It exists in reduced and oxidized forms within cells and provides significant biochemical functions, such as regulating vitamins such as vitamins D, E, and C, and facilitating detoxification. A fluorescent probe has been developed to detect copper ions selectively, sensitively, and rapidly. This report outlines the successful work on creating a peptide probe, TGN (TPE-Trp-Pro-Gly-Cln-His-NH₂), with specific Cu²⁺ detection capabilities, and a significant fluorescence recovery occurred with the addition of GSH. This indicates that the probe can detect Cu²⁺ and GSH concurrently. The detection limit for Cu²⁺ in the buffer solution was 264 nM (R² = 0.9992), and the detection limit for GSH using the TGN-Cu²⁺ complex was 919 nM (R² = 0.9917). The probe exhibits high cell permeability and low biotoxicity that make it ideal for live cell imaging in biological conditions. This peptide probe has the capability to detect Cu²⁺ and GSH in biological cells.     

Comparative genomic analyses of copper transporters and cuproproteomes reveal evolutionary dynamics of copper utilization and its link to oxygen

Copper is an essential trace element in many organisms and is utilized in all domains of life. It is often used as a cofactor of redox proteins, but is also a toxic metal ion. Intracellular copper must be carefully handled to prevent the formation of reactive oxygen species which pose a threat to DNA, lipids, and proteins. In this work, we examined patterns of copper utilization in prokaryotes by analyzing the occurrence of copper transporters and copper-containing proteins. Many organisms, including those that lack copper-dependent proteins, had copper exporters, likely to protect against copper ions that inadvertently enter the cell. We found that copper use is widespread among prokaryotes, but also identified several phyla that lack cuproproteins. This is in contrast to the use of other trace elements, such as selenium, which shows more scattered and reduced usage, yet larger selenoproteomes. Copper transporters had different patterns of occurrence than cuproproteins, suggesting that the pathways of copper utilization and copper detoxification are independent of each other. We present evidence that organisms living in oxygen-rich environments utilize copper, whereas the majority of anaerobic organisms do not. In addition, among copper users, cuproproteomes of aerobic organisms were larger than those of anaerobic organisms. Prokaryotic cuproproteomes were small and dominated by a single protein, cytochrome c oxidase. The data are consistent with the idea that proteins evolved to utilize copper following the oxygenation of the Earth.     

生物耐铜的分子机理及铜污染环境的生物联合修复

铜是动植物和人类必需的微量元素,缺乏或过多都将产生不良影响。随着社会经济的发展,人类活动对环境的干扰日益加剧,工业和农业生产活动常可导致土壤铜污染,铜已成为土壤重金属污染的主要元素之一。总结了铜在植物体内的自发内稳态调节机制,在细菌和真菌体内的吸收、分布、解毒和调节因子,同时以蚯蚓为例简要阐述了土壤动物对铜的解毒机理;从分子生物学角度对重金属铜在生物体内的代谢机理及生物对环境中过量铜的联合修复研究进展进行了综述,以期为铜污染环境的植物、微生物和动物联合修复的分子机理研究提供借鉴。     

The Arabidopsis copper transporter COPT1 functions in root elongation and pollen development

Copper plays a dual role in aerobic organisms, as both an essential and a potentially toxic element. To ensure copper availability while avoiding its toxic effects, organisms have developed complex homeostatic networks to control copper uptake, distribution, and utilization. In eukaryotes, including yeasts and mammals, high affinity copper uptake is mediated by the Ctr family of copper transporters. This work is the first report on the physiological function of copper transport in Arabidopsis thaliana. We have studied the expression pattern of COPT1 in transgenic plants expressing a reporter gene under the control of the COPT1 promoter. The reporter gene is highly expressed in embryos, trichomes, stomata, pollen, and root tips. The involvement of COPT1 in copper acquisition was investigated in CaMV35S::COPT1 antisense transgenic plants. Consistent with a decrease in COPT1 expression and the associated copper deprivation, these plants exhibit increased mRNA levels of genes that are down-regulated by copper, decreased rates of (64)Cu uptake by seedlings and reduced steady state levels of copper as measured by atomic absorption spectroscopy in mature leaves. Interestingly, COPT1 antisense plants also display dramatically increased root length, which is completely and specifically reversed by copper addition, and an increased sensitivity to growth inhibition by the copper-specific chelator bathocuproine disulfonic acid. Furthermore, COPT1 antisense plants exhibit pollen development defects that are specifically reversed by copper. Taken together, these studies reveal striking plant growth and development roles for copper acquisition by high affinity copper transporters.     

Copper transport and Alzheimer’s disease

This brief review discusses copper transport in humans, with an emphasis on knowledge learned from one of the simplest model organisms, yeast. There is a further focus on copper transport in Alzheimer’s Disease (AD). Copper homeostasis is essential for the well-being of all organisms, from bacteria to yeast to humans: survival depends on maintaining the required supply of copper for the many enzymes, dependent on copper for activity, while ensuring that there is no excess free copper, which would cause toxicity. A virtual orchestra of proteins are required to achieve copper homeostasis. For copper uptake, Cu(II) is first reduced to Cu(I) via a membrane-bound reductase. The reduced copper can then be internalised by a copper transporter where it is transferred to copper chaperones for transport and specific delivery to various organelles. Of significance are internal copper transporters, ATP7A and ATP7B, notable for their role in disorders of copper deficiency and toxicity, Menkes and Wilson’s disease, respectively. Metallothioneins and Cu/Zn superoxide dismutase can protect against excess copper in cells. It is clear too, increasing age, environmental and lifestyle factors impact on brain copper. Studies on AD suggest an important role for copper in the brain, with some AD therapies focusing on mobilising copper in AD brains. The transport of copper into the brain is complex and involves numerous players, including amyloid precursor protein, Aβ peptide and cholesterol.     

Copper chaperones: personal escorts for metal ions

Copper serves as the essential cofactor for a number of enzymes involved in redox chemistry and virtually all organisms must accumulate trace levels of copper in order to survive. However, this metal can also be toxic and a number of effective methods for sequestering and detoxifying copper prevent the metal from freely circulating inside a cell. Copper metalloenzymes are therefore faced with the challenge of acquiring their precious metal cofactor in the absence of available copper. To overcome this dilemma, all eukaryotic organisms have evolved with a family of intracellular copper binding proteins that help reserve a bioavailable pool of copper for the metalloenzymes, escort the metal to appropriate targets, and directly transfer the copper ion. These proteins have been collectively called copper chaperones. The identification of such molecules has been made possible through molecular genetic studies in the bakers' yeast Saccharomyces cerevisiae. In this review, we highlight the findings that led to a new paradigm of intracellular trafficking of copper involving the action of copper chaperones. In particular, emphasis will be placed on the ATX1 and CCS copper chaperones that act to deliver copper to the secretory pathway and to Cu/Zn superoxide dismutase in the cytosol, respectively.     

Investigation of copper homeostasis in plant cells by fluorescence lifetime imaging microscopy

Copper ions play a fundamental role in plant metabolism where its uptake and distribution within the organism is highly regulated, allowing the cells to sustain an adequate concentration. Shortage or excess of Cu can cause severe damage to the organisms endangering their survival. We recently reported a non-invasive method to follow the intracellular uptake of bivalent copper ion concentration by fluorescence lifetime microscopy of green fluorescent protein within plant cells. Measuring the fluorescence lifetime has the advantage of being independent on the fluorophore concentration and the excitation intensity. The use of GFP is beneficial because the protein can be introduced nondestructively. Here, we discuss the benefits of this approach as well as the possibility of applying this concept for the investigation of Cu redistribution and storage at the subcellular level. The fluorescence lifetime-encoded microscopic images are envisioned to map the copper distribution within plant cells not only qualitatively but even quantitatively. Time-lapse microscopy enables the following of cellular processes and the study of relevant transport mechanisms of copper in plant cells. Perspectives and necessary improvements are discussed.