Identification and characterization of the glucose dual-affinity transport system in Neurospora crassa: pleiotropic roles in nutrient transport, signaling, and carbon catabolite repression.
Identification and characterization of the glucose dual-affinity transport system in Neurospora crassa: pleiotropic roles in nutrient transport, signaling, and carbon catabolite repression.
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粗糙脉孢菌中葡萄糖双亲和力转运系统的鉴定和表征：在营养转运、信号传导和碳分解代谢物抑制中的多效性作用
DOI：
10.1186/s13068-017-0705-4
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发表时间：
2017
影响因子：
6.3
通讯作者：
Tian C
中科院分区：
文献类型：
--
作者：
Wang B;Li J;Gao J;Cai P;Han X;Tian C
背景：葡萄糖双亲和转运系统（低亲和和高亲和）是微生物用来应对环境中营养物质可用性自然波动的一种保守策略。在纤维素水解真菌中，葡萄糖感知和摄取过程被认为与纤维素酶表达调控密切相关。然而，丝状真菌中这一进化保守系统的主要分子成分的身份和功能仍然难以捉摸。在这里，我们系统地鉴定和表征了模型真菌粗神经孢子菌葡萄糖双亲和转运系统的组成部分。结果：通过RNA测序和功能转运分析，我们确定GLT-1 （Km= 18.42±3.38 mM）和HGT-1/-2 （Km= 16.13±0.95和98.97±22.02µM）分别属于低亲和力和高亲和力葡萄糖转运系统。高亲和转运体shgt-1/-2被删除后，弥补了高糖条件下的中等生长缺陷。在纤维素上生长的细胞中，同时缺失hgt-1/-2导致植物细胞壁解构基因的广泛下调。HGT-1/ 2的抑制作用与碳分解代谢抑制（CCR）和环腺苷单磷酸蛋白激酶A途径有关。HGT-1/ 2作为“受体”具有双重功能，在己糖转运体中保守的残基的改变导致葡萄糖转运功能的丧失，而CCR信号转导得以保留。结论：本研究确定GLT-1和HGT-1/ 2是葡萄糖双亲和转运系统的关键组分，在葡萄糖转运和碳代谢中发挥着不同的作用。鉴于葡萄糖双亲和转运系统在真菌物种中的广泛保守性，本研究中对其组分及其多效性的鉴定为真菌中营养物质转运、信号传导和植物细胞壁降解的分子基础提供了重要的新视角。
Background:The glucose dual-affinity transport system (low- and high-affinity) is a conserved strategy used by microorganisms to cope with natural fluctuations in nutrient availability in the environment. The glucose-sensing and uptake processes are believed to be tightly associated with cellulase expression regulation in cellulolytic fungi. However, both the identities and functions of the major molecular components of this evolutionarily conserved system in filamentous fungi remain elusive. Here, we systematically identified and characterized the components of the glucose dual-affinity transport system in the model fungusNeurospora crassa.Results:Using RNA sequencing coupled with functional transport analyses, we assigned GLT-1 (Km= 18.42 ± 3.38 mM) and HGT-1/-2 (Km= 16.13 ± 0.95 and 98.97 ± 22.02 µM) to the low- and high-affinity glucose transport systems, respectively. The high-affinity transportershgt-1/-2complemented a moderate growth defect under high glucose whenglt-1was deleted. Simultaneous deletion ofhgt-1/-2led to extensive derepression of genes for plant cell wall deconstruction in cells grown on cellulose. The suppression by HGT-1/-2 was connected to both carbon catabolite repression (CCR) and the cyclic adenosine monophosphate-protein kinase A pathway. Alteration of a residue conserved across taxa in hexose transporters resulted in a loss of glucose-transporting function, whereas CCR signal transduction was retained, indicating dual functions for HGT-1/-2 as "transceptors."Conclusions:In this study, GLT-1 and HGT-1/-2 were identified as the key components of the glucose dual-affinity transport system, which plays diverse roles in glucose transport and carbon metabolism. Given the wide conservation of the glucose dual-affinity transport system across fungal species, the identification of its components and their pleiotropic roles in this study shed important new light on the molecular basis of nutrient transport, signaling, and plant cell wall degradation in fungi.