Popinako Anna, Antonov Mikhail, Tikhonov Alexey, Tikhonova Tamara, Popov Vladimir
Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospekt. 33, bld. 2, Moscow, Russian Federation.
M. K.Ammosov North-Eastern Federal University, suite 312, Yakutsk, Republic of Sakha (Yakutia), Russian Federation.
PLoS One. 2017 May 16;12(5):e0177392. doi: 10.1371/journal.pone.0177392. eCollection 2017.
Bacteria Tv. nitratireducens and Tv. paradoxus from soda lakes grow optimally in sodium carbonate/NaCl brines at pH range from 9.5 to 10 and salinity from 0.5 to 1.5 M Na+. Octaheme nitrite reductases (ONRs) from haloalkaliphilic bacteria of genus Thioalkalivibrio are stable and active in a wide range of pH (up to 11) and salinity (up to 1 M NaCl). To establish adaptation mechanisms of ONRs from haloalkaliphilic bacteria a comparative analysis of amino acid sequences and structures of ONRs from haloalkaliphilic bacteria and their homologues from non-halophilic neutrophilic bacteria was performed. The following adaptation strategies were observed: (1) strategies specific for halophilic and alkaliphilic proteins (an increase in the number of aspartate and glutamate residues and a decrease in the number of lysine residues on the protein surface), (2) strategies specific for halophilic proteins (an increase in the arginine content and a decrease in the number of hydrophobic residues on the solvent-accessible protein surface), (3) strategies specific for alkaliphilic proteins (an increase in the area of intersubunit hydrophobic contacts). Unique adaptation mechanism inherent in the ONRs from bacteria of genus Thioalkalivibrio was revealed (an increase in the core in the number of tryptophan and phenylalanine residues, and an increase in the number of small side chain residues, such as alanine and valine, in the core).
来自苏打湖的嗜盐碱杆菌Tv. nitratireducens和Tv. paradoxus在pH值为9.5至10、盐度为0.5至1.5 M Na+的碳酸钠/氯化钠盐水中生长最佳。硫碱弧菌属嗜盐碱细菌的八聚体亚硝酸还原酶（ONR）在很宽的pH范围（高达11）和盐度范围（高达1 M NaCl）内都稳定且有活性。为了确定嗜盐碱细菌ONR的适应机制，对嗜盐碱细菌的ONR及其非嗜盐嗜中性细菌同源物的氨基酸序列和结构进行了比较分析。观察到以下适应策略：（1）嗜盐和嗜碱蛋白特有的策略（蛋白质表面天冬氨酸和谷氨酸残基数量增加，赖氨酸残基数量减少），（2）嗜盐蛋白特有的策略（精氨酸含量增加，溶剂可及蛋白质表面疏水残基数量减少），（3）嗜碱蛋白特有的策略（亚基间疏水接触面积增加）。揭示了硫碱弧菌属细菌ONR固有的独特适应机制（核心中色氨酸和苯丙氨酸残基数量增加，核心中丙氨酸和缬氨酸等小侧链残基数量增加）。
