Membrane association of active genes organizes the chloroplast nucleoid structure

• 成果类型: Article
• 署名作者: Palomar, V. Miguel; Cho, Yoonjin; Fujii, Sho; Jaksich, Sarah; Min, Ji-Hee; Schlachter, Adriana N.; Wang, Joyful; Liu, Zhengde; Wierzbicki, Andrzej T.
• 署名单位: University of Michigan System; University of Michigan; Universidad Nacional Autonoma de Mexico; Kyoto University; Hirosaki University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-14904
• DOI: 10.1073/pnas.2309244121
• 发表日期: 2024-07-09
• 关键词: extinction coefficients; thylakoid membrane; plastid nucleoids; rna-polymerase; chlorophyll-a; sigma-factor; protein; dna; arabidopsis; chromosome

摘要

DNA is organized into chromatin- like structures that support the maintenance and regulation of genomes. A unique and poorly understood form of DNA organization exists in chloroplasts, which are organelles of endosymbiotic origin responsible for photosynthesis. Chloroplast genomes, together with associated proteins, form membrane- less structures known as nucleoids. The internal arrangement of the nucleoid, molecular mechanisms of DNA organization, and connections between nucleoid structure and gene expression remain mostly unknown. We show that Arabidopsis thaliana chloroplast nucleoids have a unique sequence- specific organization driven by DNA binding to the thylakoid membranes. DNA associated with the membranes has high protein occupancy, has reduced DNA accessibility, and is highly transcribed. In contrast, genes with low levels of transcription are further away from the membranes, have lower protein occupancy, and have higher DNA accessibility. Membrane association of active genes relies on the pattern of transcription and proper chloroplast development. We propose a speculative model that transcription organizes the chloroplast nucleoid into a transcriptionally active membrane- associated core and a less active periphery.