Abstract：
The protein levels of chloroplast photosynthetic genes and genes related to the chloroplast genetic apparatus vary to adapt to different conditions. However, the underlying mechanisms governing these variations remain unclear. The chloroplast intron Maturase K is encoded within the trnK intron and has been suggested to be required for splicing several group IIA introns, including the trnK intron. In this study, we used RNA immunoprecipitation followed by high-throughput sequencing (RIP-Seq) to identify MatK\'s preference for binding to group IIA intron domains I and VI within target transcripts. Importantly, these domains are crucial for splice site selection, and we discovered alternative 5\'-splice sites in three MatK target introns. The resulting alternative trnK lariat structure showed increased accumulation during heat acclimation. The cognate codon of tRNA-K(UUU) is highly enriched in mRNAs encoding ribosomal proteins and a trnK-matK over-expressor exhibited elevated levels of the spliced tRNA-K(UUU). Ribosome profiling analysis of the overexpressor revealed a significant up-shift in the translation of ribosomal proteins compared to photosynthetic genes. Our findings suggest the existence of a novel regulatory mechanism linked to the abundance of tRNA-K(UUU), enabling the differential expression of functional chloroplast gene groups.
摘要：
叶绿体光合基因和与叶绿体遗传装置相关的基因的蛋白质水平不同，以适应不同的条件。然而,控制这些变化的潜在机制仍不清楚.叶绿体内含子MaturaseK在trnK内含子内编码，并被认为是剪接几个IIA组内含子所必需的，包括trnK内含子.在这项研究中,我们使用RNA免疫沉淀和高通量测序(RIP-Seq)来确定MatK对靶转录本内IIA组内含子结构域I和VI结合的偏好。重要的是,这些域对于剪接位点选择至关重要，我们在三个MatK靶内含子中发现了替代的5'-剪接位点。由此产生的替代trnK套索结构在热适应过程中显示出增加的积累。tRNA-K（UUU）的同源密码子在编码核糖体蛋白的mRNA中高度富集，并且trnK-matK过度表达者显示出剪接的tRNA-K（UUU）的水平升高。过表达的核糖体谱分析显示，与光合基因相比，核糖体蛋白的翻译显着上升。我们的发现表明存在一种与tRNA-K（UUU）丰度相关的新型调节机制，使功能性叶绿体基因组的差异表达成为可能。
