Characterization of tetrathionate hydrolase from the marine acidophilic sulfur-oxidizing bacterium, Acidithiobacillus thiooxidans strain SH
Characterization of tetrathionate hydrolase from the marine acidophilic sulfur-oxidizing bacterium, Acidithiobacillus thiooxidans strain SH
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DOI：
10.1080/09168451.2017.1415128
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发表时间：
2018-01
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通讯作者：
T. Kanao;Moe Onishi;Yasuyuki Kajitani;Y. Hashimoto;Tatsuya Toge;H. Kikukawa;K. Kamimura
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文献类型：
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作者：
T. Kanao;Moe Onishi;Yasuyuki Kajitani;Y. Hashimoto;Tatsuya Toge;H. Kikukawa;K. Kamimura
摘要从海洋嗜酸氧化硫硫杆菌SH菌株中部分纯化了S4-中间体（S4 I）途径的关键酶--连四硫酸盐水解酶（4THase），并对其编码基因（SH-tth）进行了鉴定。SH-Tth是一种同源二聚体，分子量为97 ± 3 kDa，含有一个大小为52 kDa的亚基。在1 M NaCl的存在下，酶活性被刺激，并在pH 3.0时显示出最大值。尽管来自A.已经报道氧化硫杆菌和密切相关的喜温嗜酸硫杆菌菌株是周质酶，SH-Tth似乎定位于细胞的外膜上，并且充当外周蛋白。此外，在硫培养的SH菌株细胞中检测到4THase活性和SH-Tth蛋白。这些结果表明，SH-Tth参与了元素硫的氧化，这与其他硫氧化菌如A. thiooxidans和A.卡尔杜斯。海洋细菌的SH-Tth表现出与湖沼细菌不同的嗜盐特征。
Abstract Tetrathionate hydrolase (4THase), a key enzyme of the S4-intermediate (S4I) pathway, was partially purified from marine acidophilic bacterium, Acidithiobacillus thiooxidans strain SH, and the gene encoding this enzyme (SH-tth) was identified. SH-Tth is a homodimer with a molecular mass of 97 ± 3 kDa, and contains a subunit 52 kDa in size. Enzyme activity was stimulated in the presence of 1 M NaCl, and showed the maximum at pH 3.0. Although 4THases from A. thiooxidans and the closely related Acidithiobacillus caldus strain have been reported to be periplasmic enzymes, SH-Tth seems to be localized on the outer membrane of the cell, and acts as a peripheral protein. Furthermore, both 4THase activity and SH-Tth proteins were detected in sulfur-grown cells of strain SH. These results suggested that SH-Tth is involved in elemental sulfur-oxidation, which is distinct from sulfur-oxidation in other sulfur-oxidizing strains such as A. thiooxidans and A. caldus. SH-Tth from the marine bacterium exhibited halophilic features distinct from those of the limnetic Af-Tth.