Cysteine dioxygenase and cysteine sulfinate decarboxylase genes of the deep-sea mussel Bathymodiolus septemdierum: possible involvement in hypotaurine synthesis and adaptation to hydrogen sulfide
Cysteine dioxygenase and cysteine sulfinate decarboxylase genes of the deep-sea mussel Bathymodiolus septemdierum: possible involvement in hypotaurine synthesis and adaptation to hydrogen sulfide
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DOI：
10.1007/s00726-014-1891-z
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发表时间：
2014-12
期刊：
影响因子：
3.5
通讯作者：
Toshihiro Nagasaki;Yuki Hongo;Tomoko Koito;Ikumi Nakamura-Kusakabe;S. Shimamura;Y. Takaki;Takao Yoshida;T. Maruyama;Koji Inoue
中科院分区：
文献类型：
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作者：
Toshihiro Nagasaki;Yuki Hongo;Tomoko Koito;Ikumi Nakamura-Kusakabe;S. Shimamura;Y. Takaki;Takao Yoshida;T. Maruyama;Koji Inoue
有人建议，居住在深海热液喷口区域的无脊椎动物使用亚磺酸亚牛磺酸（牛磺酸的前体）来防止热液喷口海水中所含硫化氢的毒性。在这个保护系统中，亚牛磺酸积聚在鳃中，这是接触硫化物的主要部位。然而，软体动物中亚牛磺酸的合成途径尚未确定。在这项研究中，我们筛选了深海贻贝Bathymodiolus septemdierum中参与亚牛磺酸合成的酶的mRNA，并克隆了编码半胱氨酸双加氧酶和半胱氨酸亚磺酸脱羧酶的cDNA。由于未检测到编码半胱胺双加氧酶和半胱氨酸裂解酶的mRNA，因此表明半胱氨酸亚磺酸途径是亚牛磺酸和牛磺酸合成的主要途径。发现这两个基因在所有检查的组织中都有表达，但鳃的表达量最高。暴露于硫化物或硫代硫酸盐中，鳃中的 mRNA 水平没有显着变化。这些结果表明 B. 的鳃。无论环境硫化物水平如何，septemdierum 都会保持这两个基因的高水平表达，并持续积累亚牛磺酸，以防止突然暴露于高水平的硫化物。
It has been suggested that invertebrates inhabiting deep-sea hydrothermal vent areas use the sulfinic acid hypotaurine, a precursor of taurine, to protect against the toxicity of hydrogen sulfide contained in the seawater from the vent. In this protective system, hypotaurine is accumulated in the gill, the primary site of sulfide exposure. However, the pathway for hypotaurine synthesis in mollusks has not been identified. In this study, we screened for the mRNAs of enzymes involved in hypotaurine synthesis in the deep-sea musselBathymodiolus septemdierumand cloned cDNAs encoding cysteine dioxygenase and cysteine sulfinate decarboxylase. As mRNAs encoding cysteamine dioxygenase and cysteine lyase were not detected, the cysteine sulfinate pathway is suggested to be the major pathway of hypotaurine and taurine synthesis. The two genes were found to be expressed in all the tissues examined, but the gill exhibited the highest expression. The mRNA level in the gill was not significantly changed by exposure to sulfides or thiosulfate. These results suggests that the gill ofB. septemdierummaintains high levels of expression of the two genes regardless of ambient sulfide level and accumulates hypotaurine continuously to protect against sudden exposure to high level of sulfide.