Polyamine transport in bacteria and yeast.
Polyamine transport in bacteria and yeast.
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DOI：
10.1042/bj3440633
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发表时间：
1999-12
期刊：
影响因子：
--
通讯作者：
K. Igarashi;Keiko Kashiwagi
中科院分区：
文献类型：
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作者：
K. Igarashi;Keiko Kashiwagi
细胞内的多胺含量受生物合成、降解和运输的调节。在大肠杆菌中，三种不同多胺转运系统的基因已被克隆和表征。两个摄取系统（腐胺特异性和亚精胺优先性）是 ABC 转运蛋白，每个系统由周质底物结合蛋白、两个跨膜蛋白和膜相关 ATP 酶组成。底物结合蛋白（PotD 和 PotF）的晶体结构已得到解决。它们由两个具有交替 β-α-β 拓扑结构的结构域组成，类似于其他周质结合蛋白。通过晶体学和定点诱变确定，多胺结合位点位于两个结构域之间的裂缝中。多胺主要被与NH(2)-（或NH-）基团相互作用的天冬氨酸和谷氨酸残基以及与多胺的亚甲基有疏水相互作用的色氨酸和酪氨酸残基识别。底物结合蛋白之一的前体 PotD 负向调节亚精胺优先摄取系统操纵子的转录，从而提供细胞多胺的另一种调节水平。第三个运输系统由 PotE 催化，介导腐胺的吸收和排泄。腐胺的吸收取决于膜电位，而排泄则涉及腐胺和鸟氨酸之间的交换反应。在酿酒酵母中，鉴定出了多胺转运蛋白（TPO1）的基因。该蛋白的性质与PotE相似，TPO1位于液泡膜上。
The polyamine content of cells is regulated by biosynthesis, degradation and transport. In Escherichia coli, the genes for three different polyamine transport systems have been cloned and characterized. Two uptake systems (putrescine-specific and spermidine-preferential) were ABC transporters, each consisting of a periplasmic substrate-binding protein, two transmembrane proteins and a membrane-associated ATPase. The crystal structures of the substrate-binding proteins (PotD and PotF) have been solved. They consist of two domains with an alternating beta-alpha-beta topology, similar to other periplasmic binding proteins. The polyamine-binding site is in a cleft between the two domains, as determined by crystallography and site-directed mutagenesis. Polyamines are mainly recognized by aspartic acid and glutamic acid residues, which interact with the NH(2)- (or NH-) groups, and by tryptophan and tyrosine residues that have hydrophobic interactions with the methylene groups of polyamines. The precursor of one of the substrate binding proteins, PotD, negatively regulates transcription of the operon for the spermidine-preferential uptake system, thus providing another level of regulation of cellular polyamines. The third transport system, catalysed by PotE, mediates both uptake and excretion of putrescine. Uptake of putrescine is dependent on membrane potential, whereas excretion involves an exchange reaction between putrescine and ornithine. In Saccharomyces cerevisiae, the gene for a polyamine transport protein (TPO1) was identified. The properties of this protein are similar to those of PotE, and TPO1 is located on the vacuolar membrane.