Polar residues in a conserved motif spanning helices 1 and 2 are functionally important in the SulP transporter family
Polar residues in a conserved motif spanning helices 1 and 2 are functionally important in the SulP transporter family
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DOI：
10.1016/j.biocel.2008.05.007
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发表时间：
2008-01-01
影响因子：
4
通讯作者：
Howitt, Susan M.
中科院分区：
文献类型：
--
作者：
Leves, Fiona P.;Tierney, M. Louise;Howitt, Susan M.
SulP家族(包括SLC26家族)是一个广泛存在于生命各个领域的阴离子转运蛋白家族，不同的成员转运不同的阴离子。我们利用对SulP家族成员螺旋1和2的序列和生物信息学分析来确定一个保守的基序，扩展了先前定义的“硫酸盐转运蛋白基序”。分析表明，除了在序列和间距上都高度保守外，螺旋1和螺旋2还含有大量的极性残基，并被预测埋藏在蛋白质内部，至少有一些面紧靠着其他螺旋。这表明该区域具有重要的功能作用，我们通过突变硫酸盐转运蛋白SHST1螺旋I和2中的极性残基进行了测试。所有的突变，即使是那些只去除了一个羟基的突变，也对运输产生了显著的影响。许多突变取消了转运，而不影响突变蛋白的质膜表达，表明这些残基具有功能作用。不同的螺旋面似乎有不同的作用，最严重的影响局限于螺旋I和2的两个相互作用面。我们的结果证实了螺旋1和2中保守的极性残基的预测重要性，并表明SHST1对硫酸盐的运输依赖于这两个螺旋之间的极性和芳香相互作用网络。皇冠版权所有(C)2008由爱思唯尔有限公司出版。保留所有权利。
The SulP family (including the SLC26 family) is a diverse family of anion transporters found in all domains of life, with different members transporting different anions. We used sequence and bioinformatics analysis of helices 1 and 2 of SulP family members to identify a conserved motif, extending the previously defined 'sulfate transporter motif. The analysis showed that in addition to being highly conserved in both sequence and spacing, helices 1 and 2 contain a significant number of polar residues and are predicted to be buried within the protein interior, with at least some faces packed closely against other helices. This suggests a significant functional role for this region and we tested this by mutating polar residues in helices I and 2 in the sulfate transporter, SHST1 All mutations made, even those removing only a single hydroxyl group, had significant effects on transport. Many mutations abolished transport without affecting plasma membrane expression of the mutant protein, suggesting a functional role for these residues. Different helical faces appear to have different roles, with the most severe effects being localised to two interacting faces of helices I and 2. Our results confirm the predicted importance of conserved polar residues in helices 1 and 2 and suggest that transport of sulfate by SHST1 is dependent on a network of polar and aromatic interactions between these two helices. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.