Cation/proton antiporter complements of bacteria: why so large and diverse?
Cation/proton antiporter complements of bacteria: why so large and diverse?
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DOI：
10.1111/j.1365-2958.2009.06842.x
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发表时间：
2009-10
影响因子：
3.6
通讯作者：
Ito M
中科院分区：
文献类型：
--
作者：
Krulwich TA;Hicks DB;Ito M
大多数细菌基因组有 5-9 个不同的基因，预计编码转运蛋白，将细胞质 Na+ 和/或 K+ 交换为细胞外的 H+，即单价阳离子/质子反向转运蛋白。相比之下，主要生活在宿主细胞内的病原体通常拥有 0-1 个这样的反向转运蛋白，而其他暴露于压力的细菌则表现出更高的数量。根据序列相似性，由这些不同基因编码的单价阳离子/质子逆向转运蛋白可分为至少八个不同的转运蛋白家族。它们使细菌能够应对高或波动的 pH、盐、温度或渗透压的挑战，但我们缺乏解释为什么需要如此多的反向转运蛋白，以及特定环境下特定反向转运蛋白类型的增值。在本期《分子微生物学》中，对“多嗜极微生物”嗜热纳特拉厌氧菌的细胞质 [Na+]、[K+]、pH 和跨膜电位的 pH 依赖性分析是评估该嗜热卤碱菌基因组中 12 个预测的单价阳离子/质子逆向转运蛋白的催化特性的背景。结果提供了多嗜极厌氧菌的适应概况，包括细胞质缓冲能力的拟议作用。他们还为两个大型单价阳离子/质子反转运蛋白家族 NhaC 和阳离子/质子反转运蛋白 3 (CPA3) 反转运蛋白家族提供了新的视角。
Most bacterial genomes have 5–9 distinct genes predicted to encode transporters that exchange cytoplasmic Na+ and/or K+ for H+ from outside the cell, i.e. monovalent cation/proton antiporters. By contrast, pathogens that live primarily inside host cells usually possess 0–1 such antiporters while other stress-exposed bacteria exhibit even higher numbers. The monovalent cation/proton antiporters encoded by these diverse genes fall into at least eight different transporter protein families based on sequence similarity. They enable bacteria to meet challenges of high or fluctuating pH, salt, temperature or osmolarity, but we lack explanations for why so many antiporters are needed and for the value-added by specific antiporter types in specific settings. In this issue of Molecular Microbiology, analyses of the pH-dependence of cytoplasmic [Na+], [K+], pH and transmembrane electrical potential in the “poly-extremophile” Natranaerobius thermophilus are the context for assessment of the catalytic properties of 12 predicted monovalent cation/proton antiporters in the genome of this thermophilic haloalkaliphile. The results provide a profile of adaptations of the poly-extremophilic anaerobe, including a proposed role of cytoplasmic buffering capacity. They also provide new perspectives on two large monovalent cation/proton antiporter families, the NhaC and the Cation/Proton antiporter-3 (CPA3) antiporter families.
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影响因子：
14.9
作者：
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通讯作者：
Paulsen IT
影响因子：
3.6
作者：
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3.6
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