Azole drugs are imported by facilitated diffusion in Candida albicans and other pathogenic fungi.
Azole drugs are imported by facilitated diffusion in Candida albicans and other pathogenic fungi.
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DOI：
10.1371/journal.ppat.1001126
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发表时间：
2010-09-30
期刊：
影响因子：
6.7
通讯作者：
White TC
中科院分区：
文献类型：
--
作者：
Mansfield BE;Oltean HN;Oliver BG;Hoot SJ;Leyde SE;Hedstrom L;White TC
尽管关于唑类抗真菌剂的作用机制和耐药性机制的知识非常丰富，但关于唑类是如何输入到致病真菌细胞中的知之甚少。在这里，在体外蓄积和进口的氟康唑（FLC）的致病真菌，白色念珠菌进行了检查。在通电的细胞中，FLC积累与ATP依赖性外排泵的表达呈负相关。在断电的细胞中，所有菌株都积累FLC，表明FLC输入不是ATP依赖性的。失能细胞中的输入动力学显示饱和动力学，Km为0.64 μ M，Vmax为0.0056 pmol/min/108个细胞，表明FLC输入通过转运蛋白的易化扩散而不是被动扩散进行。其他唑类抑制FLC进口摩尔/摩尔的基础上，这表明所有唑类利用相同的促进扩散机制。相关化合物的分析表明，竞争唑进口取决于一个芳香环和咪唑或三唑环在一个分子中。进口FLC通过促进扩散观察到其他真菌，包括新型隐球菌，酿酒酵母，和克鲁斯念珠菌，表明运输机制是保守的真菌物种。FLC输入显示不同的白色念珠菌耐药的临床分离株，这表明改变易化扩散可能是以前未表征的耐唑类药物的机制。唑类抗真菌药用于治疗人类、动物和植物的各种真菌感染。关于唑类化合物如何在真菌细胞内与其靶酶相互作用以及唑类化合物如何通过各种外排泵从真菌细胞中输出，人们已经了解了很多。改变与靶酶的相互作用和改变外排泵的表达是真菌唑类耐药的常见机制。然而，唑类化合物进入真菌细胞的机制尚不清楚，许多人认为唑类化合物是被动扩散进入细胞的。这项研究表明，唑类不是被动扩散，或主动泵入细胞。相反，唑类药物通过转运蛋白介导的易化扩散进入。唑类的促进扩散是可饱和的。所有临床上重要的唑类和许多结构相关的化合物都竞争FLC输入，而结构无关的药物不竞争。唑进口促进扩散显示在四种真菌，这表明它是常见的，如果不是所有的真菌。在一组临床分离株中观察到易化扩散改变，表明输入改变是以前未表征的耐药机制。
Despite the wealth of knowledge regarding the mechanisms of action and the mechanisms of resistance to azole antifungals, very little is known about how the azoles are imported into pathogenic fungal cells. Here the in-vitro accumulation and import of Fluconazole (FLC) was examined in the pathogenic fungus, Candida albicans. In energized cells, FLC accumulation correlates inversely with expression of ATP-dependent efflux pumps. In de-energized cells, all strains accumulate FLC, suggesting that FLC import is not ATP-dependent. The kinetics of import in de-energized cells displays saturation kinetics with a Km of 0.64 uM and Vmax of 0.0056 pmol/min/108 cells, demonstrating that FLC import proceeds via facilitated diffusion through a transporter rather than passive diffusion. Other azoles inhibit FLC import on a mole/mole basis, suggesting that all azoles utilize the same facilitated diffusion mechanism. An analysis of related compounds indicates that competition for azole import depends on an aromatic ring and an imidazole or triazole ring together in one molecule. Import of FLC by facilitated diffusion is observed in other fungi, including Cryptococcus neoformans, Saccharomyces cerevisiae, and Candida krusei, indicating that the mechanism of transport is conserved among fungal species. FLC import was shown to vary among Candida albicans resistant clinical isolates, suggesting that altered facilitated diffusion may be a previously uncharacterized mechanism of resistance to azole drugs. Azole antifungals are used to treat a wide variety of fungal infections of humans, animals and plants. A great deal is known about how the azoles interact with their target enzyme within fungal cells and how the azoles are exported from the fungal cell through various efflux pumps. Altered interactions with the target enzyme and altered efflux pump expression are common mechanisms of azole resistance in fungi. However, the mechanism by which azoles enter a fungal cell is not clear—many have assumed that azoles passively diffuse into the cell. This study demonstrates that azoles are not passively diffused, or actively pumped, into the cell. Instead, azoles are imported by facilitated diffusion, mediated by a transporter. Facilitated diffusion of azoles is saturable. All clinically important azoles, and many structurally related compounds, compete for FLC import, while structurally unrelated drugs do not compete. Azole import by facilitated diffusion is shown in four species of fungi, suggesting that it is common for most if not all fungi. Altered facilitated diffusion is observed in a collection of clinical isolates, suggesting that altered import is a previously uncharacterized mechanism of resistance.
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影响因子：
4.9
作者：
Muller, Frank-Michael C.;Staudigel, Andrea;Herrmann, Josef V.
通讯作者：
Herrmann, Josef V.
影响因子：
4.1
作者：
Baya, M;Soulounganga, P;Gérardin, P
通讯作者：
Gérardin, P
影响因子：
4.9
作者：
Albertson, GD;Niimi, M;Jenkinson, HF
通讯作者：
Jenkinson, HF
影响因子：
4.9
作者：
BOIRON, P;DROUHET, E;IMPROVISI, L
通讯作者：
IMPROVISI, L
影响因子：
2.2
作者：
Lai, Chih-Cheng;Tan, Che-Kim;Hsuch, Po-Ren
通讯作者：
Hsuch, Po-Ren