新型质体16S rRNA甲基转移酶——该蛋白的水解使植物对氧化胁迫具有可塑性

与蛋白质在细胞质和线粒体中的翻译类似，蛋白质在质体中的翻译对植物的生存及发育同样至关重要。在响应细胞内外环境因素的过程中，叶绿体内核糖体承载着调控翻译叶绿体编码蛋白的功能，这在很大程度上影响了光合效率和产量。因此，阐明在适应不断变化的外界环境过程中叶绿体编码蛋白质翻译的调控机制将有助于农业发展。最近，我们鉴定了一种对植物抵抗叶绿体胁迫至关重要的叶绿体蛋白翻译调谐子。首先，该调谐子编码了一种新型叶绿体甲基转移酶，RSMD-携带甲基转移酶(cpRCMT)，它能催化16S核糖体RNA（rRNA）甲基化；其次，叶绿体胁迫导致的活性氧（ROS）水平升高能够降低 cpRCMT 蛋白的稳定性，从而导致叶绿体编码蛋白翻译效率的降低；最后，cpRCMT 蛋白的翻译后氧化性修饰可能会促进 cpRCMT 蛋白的周转。我们研究的主要目的是探究 cpRCMT 介导的叶绿体编码蛋白的翻译过程响应环境变化的分子基础。

Plastidial translation is crucial for plant viability and development, similarly to cytosolic and mitochondrial translation. The chloroplast ribosome provides a platform in regulating chloroplast gene translation towards internal and external cues, which significantly affects photosynthetic efficiency and yield. Therefore, deciphering the regulatory mechanism of chloroplast translation to ever-changing environmental conditions would enable agricultural advances. Recently, we reveal an essential modulator of chloroplast translation, which is likely to be required in plant resilience to chloroplast stress. Firstly, the modulator encodes a novel chloroplast methyltransferase, dubbed as chloroplast RSMD-carrying methyltransferase (cpRCMT), catalyzing the 16S ribosomal RNA (rRNA) methylation. Secondly, the chloroplast stress, enhancing the levels of reactive oxygen species (ROS), negatively regulates the cpRCMT stability, resulting in the reduced chloroplast translation. Last but not least, the cpRCMT undergoes oxidative post-translational modification, which may facilitate cpRCMT turnover. The central aim of our study is to understand the molecular basis of the cpRCMT-mediated chloroplast translation in response to environmental changes. Ultimately, we expect that outputs from this project will contribute to the development of agricultural innovation.