Elucidation of the mechanisms of chloroplast intron splicing

Research Project

Project/Area Number	16K07400
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Plant molecular biology/Plant physiology
Research Institution	Osaka University
Principal Investigator	Yukari Asakura 大阪大学, 蛋白質研究所, 特任研究員 (70609677)
Project Period (FY)	2016-04-01 – 2019-03-31
Project Status	Completed (Fiscal Year 2018)
Budget Amount *help	¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000) Fiscal Year 2018: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000) Fiscal Year 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000) Fiscal Year 2016: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Keywords	葉緑体 / スプライシング / イントロン / RNA結合蛋白質 / RNA / RNA結合タンパク質
Outline of Final Research Achievements	Chloroplast genomes in higher plants encode ~ 20 group II and 1 group I introns. The CRM domain (The chloroplast RNA splicing and ribosome maturation) is an RNA binding domain that is required for splicing of group II and group I introns in higher plant chloroplasts. This domain is derived from a prokaryotic 50S pre-ribosome binding protein, YhbY. It comprises 14 or 16 orthologous groups in rice and Arabidopsis, respectively. To explore the functional repertoire of CRM domain proteins, we studied CFM1 (for CRM Family Member 1) which harbors 3 CRM domains in rice and maize. RNA co-immunoprecipiation assay showed that CFM1 in maize associates with several group II introns in chloroplasts. A rice cfm1-1 mutant possesses a point mutation conditions white or white-variegated seedling. The cfm1-1 mutant impaired in the splicing of several group II introns in chloroplasts.
Academic Significance and Societal Importance of the Research Achievements	本研究で機能を明らかにしたCFM1は、葉緑体に局在する複数個のCRMドメインを保持する蛋白群のうち６個目のスプライシング因子であり、それぞれの蛋白質でターゲットイントロンとパートナー蛋白質の組み合わせが異なっていた。CRMドメイン蛋白質群は、葉緑体やミトコンドリアの遺伝子発現を制御するために、既存のCRMドメインを2個～４個とタンデムに繋げることにより、細胞内共生以降に植物が独自に発達させたシステムであると考えられる。本研究の知見は、植物の葉緑体におけるスプライシング機構の全体像の解明や、細胞核による葉緑体の遺伝子発現制御機構の解明に寄与する。