Identification and functional analysis of the mitochondrial cysteine synthase TtCsa2 from Tetrahymena thermophila,Journal of Cellular Biochemistry

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Identification and functional analysis of the mitochondrial cysteine synthase TtCsa2 from Tetrahymena thermophila
Journal of Cellular Biochemistry ( IF 3.0 ) Pub Date : 2021-08-24 , DOI: 10.1002/jcb.30136
Hongrui Lv _{1,

2} , Lina Hu ₂ , Jing Xu _{1,

2} , Tao Bo ₂ , Wei Wang ₂

Affiliation

Cysteine is a crucial component for all organisms and plays a critical role in the structure, stability, and catalytic functions of many proteins. Tetrahymena has reverse transsulfuration and de novo pathways for cysteine biosynthesis. Cysteine synthase is involved in the de novo cysteine biosynthesis and catalyzes the production of cysteine from O-acetylserine. The novel cysteine synthase TtCSA2 was identified from Tetrahymena thermophila. The TtCSA2 showed high expression levels at the log-phase and the sexual development stage. The TtCsa2 was localized on the outer mitochondrial membrane throughout different developmental stages. However, the truncated N-terminal signal peptide mutant TtCsa2-Î”N23 was localized into the mitochondria. His-TtCsa2 was expressed in Escherichia coli and purified using affinity chromatography. The His-TtCsa2 showed O-acetylserine sulfhydrylase and serine sulfhydrylase activities. Cysteine and glutathione contents decreased in the csa2KD mutant. Furthermore, mutant cells were sensitive to cadmium and copper stresses. This study indicated that the TtCSA2 was involved in the cysteine synthesis in mitochondria and related to heavy metal stresses resistance in Tetrahymena.

中文翻译：

嗜热四膜虫线粒体半胱氨酸合酶TtCsa2的鉴定及功能分析

半胱氨酸是所有生物体的重要组成部分，在许多蛋白质的结构、稳定性和催化功能中起关键作用。四膜虫具有用于半胱氨酸生物合成的反向转硫和从头途径。半胱氨酸合酶参与半胱氨酸从头生物合成并催化从O-乙酰丝氨酸产生半胱氨酸。从嗜热四膜虫中鉴定出新型半胱氨酸合酶TtCSA2。TtCSA2在对数期和性发育阶段表现出高表达水平。TtCsa2 在整个不同发育阶段都位于线粒体外膜上。然而，截断的N-末端信号肽突变体TtCsa2-ΔN23 被本地化到线粒体中。His-TtCsa2 在大肠杆菌中表达并使用亲和层析纯化。His-TtCsa2显示出O-乙酰丝氨酸巯基解酶和丝氨酸巯基解酶活性。csa2 KD 突变体中的半胱氨酸和谷胱甘肽含量降低。此外，突变细胞对镉和铜胁迫敏感。本研究表明，TtCSA2参与线粒体中半胱氨酸的合成，与四膜虫的重金属抗逆性有关。

更新日期：2021-08-24

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