Elucidation of signal transduction mechanism of tetrapyrrole-based retrograde signaling in plants

在高等植物中，叶绿体生物发生涉及叶绿体和核基因组的协调表达，需要信息从发育中的叶绿体发送到核，反之亦然。这分别是通过所谓的逆行和顺行信号通路实现的。目前，解释逆行信号的最好模型是由叶绿体产生的一个特定的四吡咯分子作为信号来调节叶绿体发育所需的核基因的表达。虽然四吡咯被认为是细胞器来源的信号，但从细胞器到细胞核和其他细胞器的运输机制仍然很不清楚。在本研究项目中，我们对拟南芥中基于四吡咯的逆行信号转导机制进行了研究，在此研究过程中，我们成功地鉴定了参与四吡咯逆行信号转导的候选蛋白。已鉴定的ABC转运蛋白可能参与了信号转运蛋白通过叶绿体被膜的转运。此外，我们还发现，作为逆行信号最重要的组成部分，GUN1直接与四吡咯结合。这些洞察力将极大地促进我们对逆行信号机制的了解。

In higher plants, chloroplast biogenesis involves the coordinated expression of the chloroplast and nuclear genomes, requiring information to be sent from the developing chloroplasts to the nucleus and vice versa. This is achieved through so-called retrograde and anterograde signaling pathways, respectively. Currently, the best model to explain the retrograde signaling is that a specific tetrapyrrole molecules generated by chloroplast as a signal to regulate the expression of nuclear genes required for chloroplast development. Although tetrapyrrole is recognized as an organelle-derived signal, the mechanism of transport from organelle to the nucleus and other organelles is still largely unknown. In this research project, signal transduction mechanism of tetrapyrrole-based retrograde signaling in Arabidopsis thaliana has been investigated.During this research, we have succeeded in identifying candidate proteins involved in tetrapyrrole-derived retrograde signaling. It is possible that the identified ABC transporter is involved in transfer of signaling tetrapyrrole metabolites through envelope membrane of plastids. Furthermore, we found that GUN1, which is the most important component of retrograde signaling, directly binds to tetrapyrrole. These insights will significantly proceed our knowledge about the mechanism of retrograde signaling.