A conserved domain in the tail region of the Saccharomyces cerevisiae Na+/H+ antiporter (Nha1p) plays important roles in localization and salinity-resistant cell-growth
A conserved domain in the tail region of the Saccharomyces cerevisiae Na+/H+ antiporter (Nha1p) plays important roles in localization and salinity-resistant cell-growth
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DOI：
10.1093/jb/mvh016
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发表时间：
2004-01-01
影响因子：
2.7
通讯作者：
Kanazawa, H
中科院分区：
文献类型：
--
作者：
Mitsui, K;Kamauchi, S;Kanazawa, H
酿酒酵母 Na+/H+ 逆向转运蛋白 Nha1p 具有由 N 端整合膜区域和 C 端细胞质区域组成的双结构域结构。我们之前鉴定了酵母物种中保守的六个不同的细胞质结构域 (C1-C6)，在这里我们对 C1 结构域（16 个残基）进行了详细的结构功能分析。 C1 结构域的缺失会导致高盐度条件下细胞生长的广泛抑制。对具有影响 C1 结构域的单残基缺失或各种氨基酸取代的突变体进行了盐度依赖性生长和 Nha1p 定位的分析。研究发现 C1 结构域由两个子结构域组成：(i) 前三个 N 近端残基，它们与整合膜区域一起在 Nha1p 靶向细胞质膜的过程中发挥着至关重要的作用；(ii) Leu-439 和 Thr-449 之间的部分，这不是定位所必需的，但其中四个残基（Gly-440、Arg-441、His-442 和Ile-446）可能通过影响反向转运蛋白活性来影响盐度敏感细胞的生长。基于 Nha1p 的两个结构域结构与哺乳动物 Na+/H+ 反向转运蛋白的总体相似性，讨论了靠近膜区域的结构域的功能重要性。
The Saccharomyces cerevisiae Na+/H+ antiporter Nha1p has a two-domain structure consisting of an N-terminal integral membrane region and a C-terminal cytoplasmic region. We previously identified six distinct cytoplasmic domains (C1-C6) conserved among yeast species and here we performed detailed structure-function analysis of the C1 domain (16 residues). Deletion of the C1 domain causes extensive inhibition of cell-growth under high salinity conditions. Mutants with single residue deletions or various amino acid substitutions affecting the C1 domain were analyzed with respect to salinity-dependent growth and Nha1p localization. The C1 domain was found to consist of two subdomains: (i) The first three N-proximal residues, which in conjunction with the integral membrane region play a crucial role in the targeting of Nha1p to the cytoplasmic membrane, and (ii) the portion between Leu-439 and Thr-449, which is not required for localization, but in which four residues (Gly-440, Arg-441, His-442, and Ile-446) affect salinity-sensitive cell-growth by possibly influencing the antiporter activity. Based on the overall similarity of the two-domain structure of Nha1p to that of mammalian Na+/H+ antiporters, the functional importance of domains proximal to the membrane region is discussed.