School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
Plant Signal Behav. 2010 Jan;5(1):14-20. doi: 10.4161/psb.5.1.10173.
Life on earth is dependent on sulphur (S) and nitrogen (N). In plants, the second step in the reduction of sulphate and nitrate are mediated by the enzymes sulphite and nitrite reductases, which contain the iron (Fe)-containing siroheme as a cofactor. It is synthesized from the tetrapyrrole primogenitor uroporphyrinogen III in the plastids via three enzymatic reactions, methylation, oxidation and ferrochelatation. Without siroheme biosynthesis, there would be no life on earth. Limitations in siroheme should have an enormous effect on the S- and N-metabolism, plant growth, development, fitness and reproduction, biotic and abiotic stresses including growth under S, N and Fe limitations, and the response to pathogens and beneficial interaction partners. Furthermore, the vast majority of redox-reactions in plants depend on S-components, and S-containing compounds are also involved in the detoxification of heavy metals and other chemical toxins. Disturbance of siroheme biosynthesis may cause the accumulation of light-sensitive intermediates and reactive oxygen species, which are harmful, or they can function as signaling molecules and participate in interorganellar signaling processes. This review highlights the role of siroheme in these scenarios.
地球上的生命依赖于硫（S）和氮（N）。在植物中，硫酸盐和硝酸盐还原的第二步是由亚硫酸盐和亚硝酸盐还原酶介导的，它们含有作为辅助因子的含铁（Fe）的亚铁血红素。它是通过三个酶促反应，甲基化、氧化和亚铁螯合作用，从质体中的四吡咯原生物胆色素原 III 合成的。没有亚铁血红素的生物合成，地球上就没有生命。亚铁血红素的限制应该对 S 和 N 代谢、植物生长、发育、适应性和繁殖、生物和非生物胁迫（包括 S、N 和 Fe 限制下的生长以及对病原体和有益的相互作用伙伴的反应）产生巨大影响。此外，植物中绝大多数的氧化还原反应依赖于 S 成分，含 S 化合物也参与重金属和其他化学毒素的解毒。亚铁血红素生物合成的干扰可能导致对光敏感的中间体和活性氧的积累，这些物质是有害的，或者它们可以作为信号分子，并参与细胞器间的信号传递过程。这篇综述强调了亚铁血红素在这些情况下的作用。
