A novel three-TMH Na+/H+ antiporter and the functional role of its oligomerization |
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Authors: | Li Shao Tong Xu Xiutao Zheng Dandan Shao Haitao Zhang Huiwen Chen Zhenglai Zhang Mingxue Yan Heba Abdel-Motaal Juquan Jiang |
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Institution: | 1. Department of Animal Production, Faculty of Agriculture, Zagazig University, Zagazig 44511, Egypt;2. Fish Biology and Ecology Department, Central Lab for Aquaculture Research, Abassa, Abu Hammad, Sharkia, Egypt;2. University of Illinois at Urbana-Champaign, Urbana, IL, United States;3. Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States;4. College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, United States |
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Abstract: | Na+/H+ antiporters are a category of ubiquitous transmembrane proteins with various important physiological roles in almost all living organisms ranging from bacteria to humans. However, the knowledge of novel Na+/H+ antiporters remains to be broadened, and the functional roles of oligomerization in these antiporters have not yet been thoroughly understood. Here, we reported functional analysis of an unknown transmembrane protein composed of 103 amino acid residues. This protein was found to function as a Na+(Li+, K+)/H+ antiporter. To the best of our knowledge, this antiporter is the minimal one of known Na+/H+ antiporters and thus designated as NhaM to represent the minimal Na+/H+ antiporter. NhaM and its homologs have not yet been classified into any protein family. Based on phylogenetic analysis and protein alignment, we propose NhaM and its homologs to constitute a novel transporter family designated as NhaM family. More importantly, we found that NhaM is assembled with parallel protomers into a homo-oligomer and oligomerization is vital for the function of this antiporter. This implies that NhaM may adopt and require an oligomer structure for its normal function to create a similar X-shaped structure to that of the NhaA fold. Taken together, current findings not only present the proposal of a novel transporter family but also positively contribute to the functional roles of oligomerization in Na+/H+ antiporters. |
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Keywords: | NhaM family Transmembrane protein NhaA fold Oligomerization |
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