Biphasic zinc compartmentalisation in a human fungal pathogen.
Biphasic zinc compartmentalisation in a human fungal pathogen.
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DOI：
10.1371/journal.ppat.1007013
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发表时间：
2018-05
期刊：
影响因子：
6.7
通讯作者：
Wilson D
中科院分区：
文献类型：
--
作者：
Crawford AC;Lehtovirta-Morley LE;Alamir O;Niemiec MJ;Alawfi B;Alsarraf M;Skrahina V;Costa ACBP;Anderson A;Yellagunda S;Ballou ER;Hube B;Urban CF;Wilson D
营养免疫描述了宿主对基本微量营养素的操纵，包括铁、锌和锰。为了抵抗营养免疫并在宿主体内繁殖，病原微生物必须表达有效的微量营养素摄取和动态平衡系统。在这里，我们阐明了人类主要真菌白色念珠菌的细胞锌同化途径。生物信息学分析确定了9个可能的锌转运蛋白：4个细胞质输入的Zip蛋白(zrt1、zrt2、zrt3和orf19.5428)和5个细胞质输出的Znt蛋白(orf19.1536/Zrc1、orf19.3874、orf19.3769、orf19.3132和orf19.52)。只有Zrt1和Zrt2被预测定位在质膜上，在这里我们证明了在酸性pH条件下，Zrt2是白念珠菌摄取和生长所必需的。相反，ZRT1的表达高度依赖于pH，并且在pH为7及以上时可以支持ZRT2缺失菌株的生长。这一调控模式类似于远缘致病霉菌烟曲霉，表明锌转运的pH适应性在真菌中可能是保守的，我们认为环境pH塑造了真菌锌输入系统的进化。白念珠菌ZRT2基因的缺失降低了野生型小鼠的肾脏真菌负担，但对缺乏锌螯合抗菌蛋白钙保护素的小鼠却没有。中性粒细胞胞外陷阱对Δ生长的抑制作用依赖于钙保护素。这表明，在肾脏内，白念珠菌的生长是由病原体-Zrt2和宿主-钙保护素决定的。除了作为一种基本的微量营养素，锌也可能是高度有毒的，我们证明了白色念珠菌通过在称为锌小体的囊泡存储中迅速分割锌来应对这一潜在威胁。为了从机制上了解这一过程是如何发生的，我们在白色念珠菌中创建了所有五个ZNT类型转运蛋白的缺失突变体。在这里，我们表明，与酿酒酵母不同，白色念珠菌ZRC1通过锌小体锌区域化来调节锌耐受性。这种新的转运蛋白对体内的毒力和肝脏定植也是必不可少的。综上所述，我们发现锌在人类主要真菌病原体中的稳态是一个多阶段的过程，由ZRT1/ZRT2-细胞输入启动，随后是依赖于ZRC1的细胞内区域化。所有活着的生物体都必须在它们的饮食中确保某些痕量金属的安全，如铁和锌。对于感染我们的微生物来说，这些微量营养素的来源是它们宿主的组织。然而，哺乳动物已经开发出复杂的机制来操纵微生物获取痕量金属的途径--这一过程被称为营养免疫。因此，成功的病原微生物必须进化出机制，以抵消营养免疫和获得微量营养素，以便在宿主内生长并导致疾病。这场对微量营养素的争夺代表着一个关键的宿主-病原体战场。在这项研究中，我们展示了人类主要的真菌病原体白色念珠菌是如何从其环境中获取和储存锌的。我们发现锌吸收的机理基础高度依赖于周围环境的酸度。有趣的是，这种对pH的依赖似乎在真菌王国中是保守的，我们提出了一个潜在的框架来研究现存真菌物种对锌的吸收。此外，在细胞同化后，白色念珠菌将这种潜在的有毒过渡金属穿梭到称为锌小体的亚细胞间隔中。我们还表明，无论是在实验室条件下还是在侵袭性念珠菌病的实验模型中，锌的摄取和区划对白色念珠菌的生长都是至关重要的。
Nutritional immunity describes the host-driven manipulation of essential micronutrients, including iron, zinc and manganese. To withstand nutritional immunity and proliferate within their hosts, pathogenic microbes must express efficient micronutrient uptake and homeostatic systems. Here we have elucidated the pathway of cellular zinc assimilation in the major human fungal pathogen Candida albicans. Bioinformatics analysis identified nine putative zinc transporters: four cytoplasmic-import Zip proteins (Zrt1, Zrt2, Zrt3 and orf19.5428) and five cytoplasmic-export ZnT proteins (orf19.1536/Zrc1, orf19.3874, orf19.3769, orf19.3132 and orf19.52). Only Zrt1 and Zrt2 are predicted to localise to the plasma membrane and here we demonstrate that Zrt2 is essential for C. albicans zinc uptake and growth at acidic pH. In contrast, ZRT1 expression was found to be highly pH-dependent and could support growth of the ZRT2-null strain at pH 7 and above. This regulatory paradigm is analogous to the distantly related pathogenic mould, Aspergillus fumigatus, suggesting that pH-adaptation of zinc transport may be conserved in fungi and we propose that environmental pH has shaped the evolution of zinc import systems in fungi. Deletion of C. albicans ZRT2 reduced kidney fungal burden in wild type, but not in mice lacking the zinc-chelating antimicrobial protein calprotectin. Inhibition of zrt2Δ growth by neutrophil extracellular traps was calprotectin-dependent. This suggests that, within the kidney, C. albicans growth is determined by pathogen-Zrt2 and host-calprotectin. As well as serving as an essential micronutrient, zinc can also be highly toxic and we show that C. albicans deals with this potential threat by rapidly compartmentalising zinc within vesicular stores called zincosomes. In order to understand mechanistically how this process occurs, we created deletion mutants of all five ZnT-type transporters in C. albicans. Here we show that, unlike in Saccharomyces cerevisiae, C. albicans Zrc1 mediates zinc tolerance via zincosomal zinc compartmentalisation. This novel transporter was also essential for virulence and liver colonisation in vivo. In summary, we show that zinc homeostasis in a major human fungal pathogen is a multi-stage process initiated by Zrt1/Zrt2-cellular import, followed by Zrc1-dependent intracellular compartmentalisation. All living organisms must secure certain trace metals such as iron and zinc in their diets. For the microbes that infect us, the source of these micronutrients is the tissues of their host. However, mammals have developed sophisticated mechanisms to manipulate microbial access to trace metals–a process called nutritional immunity. Therefore, successful pathogenic microorganisms must have evolved mechanisms to counteract nutritional immunity and acquire micronutrients in order to grow within their hosts and cause disease. This struggle for micronutrients represents a key host-pathogen battleground. In this study we demonstrate how the major human fungal pathogen, Candida albicans, acquires and stores zinc from its environment. We find that the mechanistic basis of zinc uptake is highly dependent on the acidity of the surrounding environment. Interestingly, this pH-dependence appears conserved in the fungal kingdom and we propose a potential framework for the evolution of zinc uptake in extant fungal species. Moreover, following cellular assimilation, C. albicans shuttles this potentially toxic transition metal into subcellular compartments called zincosomes. We also show that both zinc uptake and compartmentalisation are critical for C. albicans growth, both under laboratory conditions and in experimental models of invasive candidiasis.
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影响因子：
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作者：
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通讯作者：
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影响因子：
6.7
作者：
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作者：
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通讯作者：
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DOI：
10.1098/rspb.2016.0648
发表时间：
2016-05-11
影响因子：
4.7
作者：
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通讯作者：
Preston, G. M.