Carboxyl-terminal hydrophilic tail of a NhaP type Na+/H+ antiporter from cyanobacteria is involved in the apparent affinity for Na+ and pH sensitivity.
Carboxyl-terminal hydrophilic tail of a NhaP type Na+/H+ antiporter from cyanobacteria is involved in the apparent affinity for Na+ and pH sensitivity.
复制标题
蓝藻 NhaP 型 Na /H 逆向转运蛋白的羧基末端亲水尾部参与对 Na 的表观亲和力和 pH 敏感性。
DOI：
10.1016/j.abb.2006.02.013
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发表时间：
2006
影响因子：
3.9
通讯作者：
T. Takabe
中科院分区：
文献类型：
--
作者：
Rungaroon Waditee;T. Buaboocha;Mariko Kato;T. Hibino;Shigetoshi Suzuki;Tatsunosuke Nakamura;T. Takabe
关于原核 Na+/H+ 反向转运蛋白 C 端亲水尾的信息很少。为了解决 C 末端尾部的功能特性，构建了该结构域的截短突变体。来自集胞藻 PCC6803 的 NhaP1 型逆向转运蛋白 (SynNhaP1) C 端氨基酸残基的截断并未改变 Vmax 值，但使 Na+ 和 Li+ 的 Km 值增加约 3 至 15 倍。耐盐蓝细菌 Aphanothece halophytica (ApNhaP1) C 末端尾部的截断显着降低了 Vmax，尽管它没有改变 Na+ 的 Km 值。 SynNhaP1 的 C 末端部分在大肠杆菌中表达并纯化为 16kDa 可溶性蛋白。将纯化的多肽添加到表达C端截短的SynNhaP1的膜囊泡中增加了交换活性。 C 末端尾部的 Glu519 和 Glu521 更改为 Lys，改变了 Na+/H+ 和 Li+/H+ 交换活性的 pH 依赖性。这些结果表明，C 端结构域的特定酸性氨基酸残基对于交换活性的 Kman 和 pH 依赖性起着重要作用。
Little information is available on the C-terminal hydrophilic tails of prokaryotic Na+/H+antiporters. To address functional properties of the C-terminal tail, truncation mutants in this domain were constructed. Truncation of C-terminal amino acid residues of NhaP1 type antiporter from Synechocystis PCC6803 (SynNhaP1) did not change the Vmaxvalues, but increased the Kmvalues for Na+and Li+about 3 to 15-fold. Truncation of C-terminal tail of a halotolerant cyanobacterium Aphanothece halophytica (ApNhaP1) significantly decreased the Vmaxalthough it did not alter the Kmvalues for Na+. The C-terminal part of SynNhaP1 was expressed in E. coli and purified as a 16kDa soluble protein. Addition of purified polypeptide to the membrane vesicles expressing the C-terminal truncated SynNhaP1 increased the exchange activities. Change of Glu519 and Glu521 to Lys in C-terminal tail altered the pH dependence of Na+/H+and Li+/H+exchange activities. These results indicate that the specific acidic amino acid residues at C-terminal domain play important roles for the Kmand the pH dependence of the exchange activity.