A novel NhaD-type Na+/H+ antiporter from the moderate halophile and alkaliphile Halomonas alkaliphila

作者：Yan‐Hong Wang, Na Song, Lina Yang, Heba Abdel-Motaal, Rui Zhang, Zhenglai Zhang, Fankui Meng, Juquan Jiang · 发表于：Canadian Journal of Microbiology · 年份：2017 · DOI：10.1139/cjm-2017-0104 · 被引用次数：15 · 研究领域：Plant nutrient uptake and metabolism、Bacterial Genetics and Biotechnology、Legume Nitrogen Fixing Symbiosis

In this study, a NhaD-type Na + /H + antiporter gene designated Ha-nhaD was obtained by selection of genomic DNA from the moderate halophile and alkaliphile Halomonas alkaliphila in Escherichia coli KNabc lacking 3 major Na + /H + antiporters. The presence of Ha-NhaD conferred tolerance of E. coli KNabc to NaCl up to 0.6 mol·L –1 and to LiCl up to 0.2 mol·L –1 and to an alkaline pH. pH-dependent Na + (Li + )/H + antiport activity was detected from everted membrane vesicles prepared from E. coli KNabc/pUC-nhaD but not those of KNabc/pUC18. Ha-NhaD exhibited Na + (Li + )/H + antiport activity over a wide pH range from 7.0 to 9.5, with the highest activity at pH 9.0. Protein sequence alignment and phylogenetic analysis revealed that Ha-NhaD is significantly different from the 7 known NhaD-type Na + /H + antiporters, including Dw-NhaD, Dl-NhaD, Vp-NhaD, Vc-NhaD, Aa-NhaD, He-NhaD, and Ha-NhaD1. Although Ha-NhaD showed a closer phylogenetic relationship with Ha-NhaD2, a significant difference in pH-dependent activity profile exists between Ha-NhaD and Ha-NhaD2. Taken together, Ha-nhaD encodes a novel pH-dependent NhaD-type Na + /H + antiporter.