Na+/H+逆向转运蛋白在生物体耐受高盐碱环境及工农业生产应用中具有重要作用和潜力。其中的NhaD型转运蛋白具有高的转运活性但相关研究较少，尤其是分子转运机制仅见少量定点突变研究报道。课题以来源于中度嗜盐嗜碱菌Halomonas的两个高活性NhaD型同源Na+/H+转运蛋白为研究对象，对NhaD蛋白的环境应答及分子转运机制进行深入研究。基于两个蛋白的生长互补及转运pH依赖性显著差异，通过跨膜结构预测和序列比对构建系列嵌合体和突变体，研究NhaD蛋白中与环境应答、离子结合及pH感应相关的关键区域与位点；利用基因回补技术对敲除菌株ΔnhaD1、ΔnhaD2进行各突变蛋白的回补表达，同时选择Halomonas elongata及Vibrio cholerae 来源的NhaD型蛋白进行嵌合体和突变体构建，验证关键区域和位点功能，最终系统阐述NhaD型蛋白的环境应答及分子转运机制。

Na+/H+ antiporters play important even crucial roles in salt and alkali tolerance of organisms, and have great potentials in industry and agriculture. As the antiporter with high transport activity, research referring NhaD antiporters is limited, especially on its molecular transport mechanism. The project will focus on two NhaD type antiporters deriving from Halomonas strain, which possessing great difference in growth complementation and pH dependence of Na+ transporting. By using transmembrance structure predication and sequence alignment, various chimaeras and mutants will be constructed, and used for exploring important regions or sites referring environmental response, cation binding and pH sensitivity; In addition, roles of these important regions or sites will be confirmed by complementation experiments, by constructing various complementary strain from ΔnhaD1、ΔnhaD2 and testing their sensitivities upon salinity and alkali stress. In addition, important chimaeras and mutants will be constructed from other NhaD type antiportersof Halomonas elongata and Vibrio cholera. Based on this research, we will illustrate the molecular mechanisms of NhaD type proteins for environmental response and ion transporting.