State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, 210023, China.
Protoplasma. 2021 Mar;258(2):371-378. doi: 10.1007/s00709-020-01578-x. Epub 2020 Oct 27.
Chloroplasts are semi-autonomous organelles, with more than 95% of their proteins encoded by the nuclear genome. The chloroplast-to-nucleus retrograde signals are critical for the nucleus to coordinate its gene expression for optimizing or repairing chloroplast functions in response to changing environments. In chloroplasts, the pentatricopeptide-repeat protein GENOMES UNCOUPLED 1 (GUN1) is a master switch that senses aberrant physiological states, such as the photooxidative stress induced by norflurazon (NF) treatment, and represses the expression of photosynthesis-associated nuclear genes (PhANGs). However, it is largely unknown how the retrograde signal is transmitted beyond GUN1. In this study, a protein GUN1-INTERACTING PROTEIN 1 (GIP1), encoded by At3g53630, was identified to interact with GUN1 by different approaches. We demonstrated that GIP1 has both cytosol and chloroplast localizations, and its abundance in chloroplasts is enhanced by NF treatment with the presence of GUN1. Our results suggest that GIP1 and GUN1 may function antagonistically in the retrograde signaling pathway.
叶绿体是半自主细胞器，其 95%以上的蛋白质由核基因组编码。叶绿体到细胞核的逆行信号对于核来说至关重要，核可以通过协调其基因表达来优化或修复叶绿体功能，以响应不断变化的环境。在叶绿体中，五肽重复蛋白 GENOMES UNCOUPLED 1（GUN1）是一个主开关，它可以感知异常的生理状态，如 NF 处理引起的光氧化应激，并抑制与光合作用相关的核基因（PhANGs）的表达。然而，逆行信号如何超越 GUN1 传递还在很大程度上是未知的。在这项研究中，通过不同的方法鉴定出一个由 At3g53630 编码的蛋白 GUN1-INTERACTING PROTEIN 1（GIP1）与 GUN1 相互作用。我们证明 GIP1 具有细胞质和叶绿体定位，并且在 NF 处理存在 GUN1 的情况下，其在叶绿体中的丰度增加。我们的结果表明，GIP1 和 GUN1 可能在逆行信号通路中发挥拮抗作用。
