Exploring the dynamism of chloroplastic chromosomes, nucleoids

2021 Fiscal Year Final Research Report

• Project/Area Number: 18H02460
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 44030:Plant molecular biology and physiology-related
• Research Institution: Kyoto University
• Principal Investigator: Nishimura Yoshiki 京都大学, 理学研究科, 助教 (70444099)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 葉緑体DNA / 核様体

Outline of Final Research Achievements

Compaction of bulky DNA is a universal issue for all DNA-based life forms. Both Chloroplasts and mitochondria maintain their own multi-copy genomes organized as nucleoids, but the mechanism of DNA compaction remains obscure. Here, we discovered a chloroplast nucleoid protein (HBD1) that is highly similar to major mitochondrial nucleoid proteins transcription factor A, mitochondrial (TFAM), and ARS binding factor 2 protein (Abf2p) in terms of possessing two DNA-binding high mobility group box (HMG-box) domains. Our analyses of HBD1 based on DNA origami/atomic force microscopy showed that HBD1 is capable of compacting DNA by introducing U-turns and cross-strand bridges with the two HMG-box domains, indicating that proteins with two HMG-box domains could compact DNA in both mitochondrial and chloroplast nucleoids.

Free Research Field

植物分子遺伝学

Academic Significance and Societal Importance of the Research Achievements

葉緑体において、2つのDNA結合部位（HMG-boxドメイン）を持つタンパク質(HBD1)が、DNAクリップとしてDNAを折り曲げ、架橋することでDNAを折りたたみ、核様体を構築していることが示された。ここで得られた知見は葉緑体工学における葉緑体ゲノムの安定性や遺伝子発現制御に関する新技術開発、さらにヒトを含む動物・植物におけるミトコンドリア核様体の機能解析への応用、医学・農学をふくむ様々な分野への展開が期待される。