The short C-terminal hydrophilic domain of NhaH Na^+/H^+ antiporter from Halobacillus dabanensis with roles in resistance to salt and in pH sensing |
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作者姓名: | YANG LiFu ;ZHANG Bo ;WANG Lei ;YANG SuSheng |
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作者单位: | [1]1Department of Microbiology and Immunology, College of Biological Sciences, and Key Laboratory of Agro-Microbial Resource and Application, Ministry of Agriculture, China Agricultural University, Beijing 100193, China; [2]Rubber Research Institute, and Key Laboratory of Physiology for Tropical Crops, Ministry of Agriculture, Chinese Academy of Tropical Agricultural Sciences, Danzhou, Hainan 571737, China |
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基金项目: | Supported by the National High Technology Research and Development Program of China (Grant No. 2003AA241150), and International Cooperation Program for Science and Technology (Grant No. 2006DFA31060) |
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摘 要: | The Na^+/H^+ antiporter plays key roles in maintaining low cytoplasmic NaNa^+ level and pH homeostasis, while little is known about the Carboxyl-terminal hydrophilic tails of prokaryotic antiporters. In our previous study, the first Na^+/H^+ antiporter gene nhaH from moderate halophiles was cloned from Halobacillus dabanensis D-8 by functional complementation. A topological model suggested that only nine amino acid residues (^395PLIKKLGMI403) existed in the hydrophilic C-terminal domain of NhaH. The C-terminal truncated mutant of NhaH was constructed by PCR strategy and designated as nhaH△C. Salt tolerance experiment demonstrated that the deletion of hydrophilic C-terminal nine amino acid residues significantly inhibited the complementation ability of E. coil KNabc, in which three main Na^+/H^+ antiporters nhaA, nhaB and chaA were deleted. Everted membrane vesicles prepared from E. coil KNabc/nhaHAC decreased both Na^+/H^+ and Li^+/H^+ exchange activities of NhaH, and also resulted in an acidic shift of its pH profile for Na^+, indicating a critical role of the short C-terminal domain of NhaH antiporter in alkali cation binding/translocation and pH sensing.
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关 键 词: | 反向转运 亲水性 基因表达 生物学 |
收稿时间: | 2008-01-14 |
修稿时间: | 2008-06-03 |
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