Characterization of an amino acid permease from the endomycorrhizal fungus Glomus mosseae
Characterization of an amino acid permease from the endomycorrhizal fungus Glomus mosseae
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DOI：
10.1104/pp.108.117820
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发表时间：
2008-05-01
期刊：
影响因子：
7.4
通讯作者：
Bonfante, Paola
中科院分区：
文献类型：
--
作者：
Cappellazzo, Gilda;Lanfranco, Luisa;Bonfante, Paola
丛枝菌根(AM)真菌能够利用有机氮源，但控制这种吸收的分子机制仍不清楚。基于聚合酶链式反应的方法、生物信息学工具和异源表达系统已被用于鉴定AM真菌Glomus Mosseae的氨基酸渗透酶(GmosAAP1)的编码序列。GmosAAP1显示出与其他真菌氨基酸透皮相似的一级和二级结构。对多种氨基酸摄取系统缺陷的酵母突变株的功能互补和摄取实验表明，GmosAAP1能够通过质子耦合、依赖于pH和能量的过程转运脯氨酸。竞争性测试表明，GmosAAP1与非极性和疏水性氨基酸结合，从而显示出相对特异的底物光谱。在根外真菌结构中检测到GmosAAP1mRNAs。转录本丰度在暴露于有机氮时增加，特别是当供应浓度为2 mM时。这些发现表明，GmosAAP1在氨基酸获取的第一步中发挥了作用，允许从土壤中直接吸收氨基酸，并扩展了AM真菌开发土壤资源的分子工具。
Arbuscular mycorrhizal (AM) fungi are capable of exploiting organic nitrogen sources, but the molecular mechanisms that control such an uptake are still unknown. Polymerase chain reaction-based approaches, bioinformatic tools, and a heterologous expression system have been used to characterize a sequence coding for an amino acid permease (GmosAAP1) from the AM fungus Glomus mosseae. The GmosAAP1 shows primary and secondary structures that are similar to those of other fungal amino acid permeases. Functional complementation and uptake experiments in a yeast mutant that was defective in the multiple amino acid uptake system demonstrated that GmosAAP1 is able to transport proline through a proton-coupled, pH- and energy-dependent process. A competitive test showed that GmosAAP1 binds nonpolar and hydrophobic amino acids, thus indicating a relatively specific substrate spectrum. GmosAAP1 mRNAs were detected in the extraradical fungal structures. Transcript abundance was increased upon exposure to organic nitrogen, in particular when supplied at 2 mM concentrations. These findings suggest that GmosAAP1 plays a role in the first steps of amino acid acquisition, allowing direct amino acid uptake from the soil and extending the molecular tools by which AM fungi exploit soil resources.