Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstraße 13, Berlin, 10115, Germany.
New Phytol. 2023 Jun;238(6):2545-2560. doi: 10.1111/nph.18906. Epub 2023 Apr 13.
Tetrapyrrole biosynthesis (TBS) is a dynamically and strictly regulated process. Disruptions in tetrapyrrole metabolism influence many aspects of plant physiology, including photosynthesis, programmed cell death (PCD), and retrograde signaling, thus affecting plant growth and development at multiple levels. However, the genetic and molecular basis of TBS is not fully understood. We report here PCD8, a newly identified thylakoid-localized protein encoded by an essential gene in Arabidopsis. PCD8 knockdown causes a necrotic phenotype due to excessive chloroplast damage. A burst of singlet oxygen that results from overaccumulated tetrapyrrole intermediates upon illumination is suggested to be responsible for cell death in the knockdown mutants. Genetic and biochemical analyses revealed that PCD8 interacts with ClpC1 and a number of TBS enzymes, such as HEMC, CHLD, and PORC of TBS. Taken together, our findings uncover the function of chloroplast-localized PCD8 and provide a new perspective to elucidate molecular mechanism of how TBS is finely regulated in plants.
四吡咯生物合成（TBS）是一个动态且严格调控的过程。四吡咯代谢的紊乱会影响植物生理学的许多方面，包括光合作用、程序性细胞死亡（PCD）和逆行信号转导，从而在多个层次上影响植物的生长和发育。然而，TBS 的遗传和分子基础尚未完全了解。我们在这里报告了 PCD8，这是一种新鉴定的定位于类囊体的蛋白，由拟南芥中一个必需基因编码。PCD8 的敲低会导致由于叶绿体过度损伤而产生的坏死表型。在光照下，由于四吡咯中间产物的过度积累而产生的单线态氧的爆发，被认为是导致敲低突变体细胞死亡的原因。遗传和生化分析表明，PCD8 与 ClpC1 和许多 TBS 酶相互作用，如 TBS 的 HEMC、CHLD 和 PORC。总之，我们的发现揭示了定位于叶绿体的 PCD8 的功能，并为阐明植物中 TBS 如何精细调控的分子机制提供了新的视角。
