Glycerophosphocholine Utilization by Candida albicans ROLE OF THE Git3 TRANSPORTER IN VIRULENCE
Glycerophosphocholine Utilization by Candida albicans ROLE OF THE Git3 TRANSPORTER IN VIRULENCE
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DOI：
10.1074/jbc.m113.505735
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发表时间：
2013-11-22
影响因子：
4.8
通讯作者：
Patton-Vogt, Jana
中科院分区：
文献类型：
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作者：
Bishop, Andrew C.;Ganguly, Shantanu;Patton-Vogt, Jana
白色念珠菌含有4个开放阅读框(GIT1、2、3、4)，编码与甘油磷酸二酯代谢产物运输有关的蛋白。以前，我们报道了Git1，由ORF 19.34编码，负责完整的甘油磷酸肌醇的运输，但不负责甘油磷酸胆碱(GroPCho)的运输。在这里，我们报告了一株同时缺乏GIT3(ORF 19.1979)和GIT4(ORF 19.1980)的菌株不能将[H-3]GroPCho转运到细胞内。在没有GroPCho转运体的情况下，白色念珠菌可以通过胞外水解机制来利用GroPCho。当GIT3或GIT4重新整合到基因组中时，可以观察到[H-3]GroPCho的可测量摄取。转运分析和动力学分析表明，Git3具有较大的转运速度。我们提出了GDE1(开放阅读框19.3936)编码一种具有甘油磷酸二酯酶活性的酶来对抗GroPCho的证据。GDE1的纯合缺失导致内部GroPCho的积聚，通过将GDE1重新整合到基因组中，GDE1恢复到野生型水平。转录调节因子Pho4被证明调节GIT3、GIT4和GDE1的表达。最后，在播散性念珠菌病的小鼠模型中，Git3被证明是完全毒力所必需的，并且Git3序列的同源基因存在于其他致病的念珠菌物种中。综上所述，我们已经表征了白色念珠菌利用GroPCho的多个方面，并证明了GroPCho运输在宿主生物的生长中发挥着关键作用。
Candida albicans contains four ORFs (GIT1,2,3,4) predicted to encode proteins involved in the transport of glycerophosphodiester metabolites. Previously, we reported that Git1, encoded by ORF 19.34, is responsible for the transport of intact glycerophosphoinositol but not glycerophosphocholine (GroPCho). Here, we report that a strain lacking both GIT3 (ORF 19.1979) and GIT4 (ORF 19.1980) is unable to transport [H-3]GroPCho into the cell. In the absence of a GroPCho transporter, C. albicans can utilize GroPCho via a mechanism involving extracellular hydrolysis. Upon reintegration of either GIT3 or GIT4 into the genome, measurable uptake of [H-3]GroPCho is observed. Transport assays and kinetic analyses indicate that Git3 has the greater transport velocity. We present evidence that GDE1 (ORF 19.3936) codes for an enzyme with glycerophosphodiesterase activity against GroPCho. Homozygous deletion of GDE1 results in a buildup of internal GroPCho that is restored to wild type levels by reintegration of GDE1 into the genome. The transcriptional regulator, Pho4, is shown to regulate the expression of GIT3, GIT4, and GDE1. Finally, Git3 is shown to be required for full virulence in a mouse model of disseminated candidiasis, and Git3 sequence orthologs are present in other pathogenic Candida species. In summary, we have characterized multiple aspects of GroPCho utilization by C. albicans and have demonstrated that GroPCho transport plays a key role in the growth of the organism in the host.