Mitochondrial dysfunction is related to common age-related disorders, including neurodegenerative diseases, metabolic syndrome, and carcinogenesis. Therefore, maintaining the functionality and integrity of mitochondria is important for human health. Herein, we found that sulfide:quinone oxidoreductase (Sqr), which oxidizes hydrogen sulfide to reactive sulfur species (RSS), was indispensable to mitochondria health in the eukaryotic model microorganism Schizosaccharomyces pombe. Sqr knock-out led to morphological changes and functional deficiencies of mitochondria and apoptosis in S. pombe. The Sqr knock-out strain displayed the same phenotypes as the cysteine-synthesis-deficient strain, and cysteine addition complemented the effects caused by Sqr knock-out. In S. pombe, Sqr was the main RSS producer in mitochondria, and RSS instead of H₂S was used by cysteine synthase to synthesize cysteine. This finding rewrites the cysteine biosynthesis route in S. pombe and may also in other eukaryotes and prokaryotes, and highlights the importance of cysteine and RSS in maintaining mitochondrial health.

线粒体功能障碍与常见的年龄相关疾病有关，包括神经退行性疾病、代谢综合征和致癌作用。因此，保持线粒体的功能和完整性对​​人类健康很重要。在此，我们发现硫化物：醌氧化还原酶 (Sqr) 将硫化氢氧化为活性硫物质 (RSS)，对真核模型微生物粟酒裂殖酵母中的线粒体健康至关重要。Sqr 敲除导致粟酒裂殖酵母中线粒体的形态学变化和功能缺陷以及细胞凋亡。Sqr 敲除菌株显示出与半胱氨酸合成缺陷菌株相同的表型，并且半胱氨酸添加补充了 Sqr 敲除引起的影响。在S. pombe, Sqr 是线粒体中主要的 RSS 生产者，半胱氨酸合酶使用RSS 代替 H ₂ S 合成半胱氨酸。这一发现改写了粟酒和其他真核生物和原核生物中的半胱氨酸生物合成途径，并强调了半胱氨酸和 RSS 在维持线粒体健康方面的重要性。