A new family of high-affinity transporters for adenine, cytosine, and purine derivatives in arabidopsis
A new family of high-affinity transporters for adenine, cytosine, and purine derivatives in arabidopsis
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DOI：
10.1105/tpc.12.2.291
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发表时间：
2000-02-01
期刊：
影响因子：
11.6
通讯作者：
Frommer, WB
中科院分区：
文献类型：
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作者：
Gillissen, B;Bürkle, L;Frommer, WB
在包括植物在内的许多生物体中，核酸碱基和衍生物像咖啡因一样穿过质膜运输。细胞分裂素是一种重要的激素，在结构上与腺嘌呤相关，主要在根尖产生，从那里它们被转运到芽中以控制许多生理过程。互补的酵母突变体缺陷的腺嘌呤摄取（Fc γ 2）与拟南芥cDNA表达文库的基因，AtPUP 1（拟南芥嘌呤permease 1），属于一个大的基因家族（AtPUP 1至AtPUP 15）编码一类新的小，完整的膜蛋白的鉴定。AtPUP 1以高亲和力转运腺嘌呤和胞嘧啶。摄取是能量依赖性的，逆着浓度梯度发生，并且对质子载体敏感，可能指示次级主动转运。竞争研究表明，嘌呤衍生物（例如，次黄嘌呤），植物激素（例如，玉米素和激动素）和生物碱（例如咖啡因）是腺嘌呤和胞嘧啶摄取的有效抑制剂。细胞分裂素的抑制作用是竞争性的（竞争性抑制常数Ki = 20 ~ 35 μ M），表明细胞分裂素是由该系统转运的。AtPUP 1在除根外的所有器官中表达，表明该基因编码芽中根来源的核酸碱基衍生物的摄取系统，或者它通过韧皮部从芽中输出核酸碱基类似物。其他家族成员可能对核酸碱基有不同的亲和力，可能充当核苷、核苷酸及其衍生物的转运蛋白。
In many organisms, including plants, nucleic acid bases and derivatives suck as caffeine are transported across the plasma membrane. Cytokinins, important hormones structurally related to adenine, are produced mainly in root apices, from where they are translocated to shoots to control a multitude of physiological processes. Complementation of a yeast mutant deficient in adenine uptake (fcy2) with an Arabidopsis cDNA expression library enabled the identification of a gene, AtPUP1 (for Arabidopsis thaliana purine permease1), belonging to a large gene family (AtPUP1 to AtPUP15) encoding a new class of small, integral membrane proteins. AtPUP1 transports adenine and cytosine with high affinity. Uptake is energy dependent, occurs against a concentration gradient, and is sensitive to protonophores, potentially indicating secondary active transport, Competition studies show that purine derivatives (e.g., hypoxanthine), phytohormones (e.g., zeatin and kinetin), and alkaloids (e.g,, caffeine) are potent inhibitors of adenine and cytosine uptake. Inhibition by cytokinins is competitive (competitive inhibition constant K-i = 20 to 35 mu M), indicating that cytokinins are transported by this system. AtPUP1 is expressed in all organs except roots, indicating that the gene encodes an uptake system for root-derived nucleic acid base derivatives in shoots or that it exports nucleic acid base analogs from shoots by way of the phloem. The other family members may have different affinities for nucleic acid bases, perhaps functioning as transporters for nucleosides, nucleotides, and their derivatives.