A mutagenic study identifying critical residues for the structure and function of rice manganese transporter OsMTP8.1.
A mutagenic study identifying critical residues for the structure and function of rice manganese transporter OsMTP8.1.
复制标题
一项确定水稻锰转运蛋白 OsMTP8.1 结构和功能关键残基的诱变研究。
DOI：
10.1038/srep32073
复制
发表时间：
2016-08-24
影响因子：
4.6
通讯作者：
Zhang W
中科院分区：
文献类型：
--
作者：
Chen X;Li J;Wang L;Ma G;Zhang W
水稻（Oryza sativa） MTP8.1 （OsMTP8.1）是一种阳离子扩散促进剂家族的叶绿体定位锰转运蛋白。在此，我们基于锰敏感酵母的位点定向和随机诱变和互补实验，结合基于大肠杆菌CDF家族成员EcYiiP晶体结构的三维（3D）结构建模，对OsMTP8.1进行了结构-功能分析。在OsMTP8.1中，EcYiiP保留了两个金属结合位点，一个在跨膜螺旋TM2和TM5之间，另一个是细胞质c端。除了这两个金属结合位点外，可能还存在其他的mn结合位点，例如在CTD的最末端。两个残基（R167和L296）可能在CTDs的铰链运动中起重要作用。E357A和V374D等几种突变可能影响二聚体的形成，S132A可能引起构象变化，导致输运功能丧失或金属选择性改变。OsMTP8.1的n端不具有Mn转运活性，NTD的真正功能有待进一步研究。本研究结果说明了OsMTP8.1在Mn转运活性中的结构-功能关系，也可应用于其他植物Mn- cdf蛋白。
Rice (Oryza sativa) MTP8.1 (OsMTP8.1) is a tonoplast-localized manganese transporter of the cation diffusion facilitator family. Here we present a structure-function analysis of OsMTP8.1 based on the site-directed and random mutagenesis and complementation assays in manganese hypersensitive yeast, in combination with three-dimensional (3D) structure modeling based on the crystal structure of the Escherichia coli CDF family member, EcYiiP. Two metal-binding sites are conserved in OsMTP8.1 with EcYiiP, one is between transmembrane helices TM2 and TM5, the other is the cytoplasmic C-terminus. In addition to these two metal-binding sites, there may exist other Mn-binding sites such as that at the very end of the CTD. Two residues (R167 and L296) may play an important role for the hinge-like movement of CTDs. Several mutations such as E357A and V374D may affect dimer formation, and S132A may induce a conformational change, resulting in a loss of transport function or modification in metal selectivity. The N-terminus of OsMTP8.1 was not functional for Mn transport activity, and the real function of NTD remains to be investigated in the future. The findings of the present study illustrate the structure-function relationship of OsMTP8.1 in Mn transport activity, which may also be applied to other plant Mn-CDF proteins.