生物
RNA解旋酶A
细胞生物学
叶绿体
叶绿体DNA
解旋酶
核糖核酸
基因
生物化学
作者
Xin Chai,X Wang,Liwei Rong,M. Luo,Li Yuan,Qiuxin Li,Baoye He,Jingjing Jiang,Daili Ji,Min Ouyang,Qingtao Lu,Lixin Zhang,Jean‐David Rochaix,Wei Chi
摘要
Summary R‐loops, three‐stranded nucleic acid structures consisting of a DNA: RNA hybrid and displaced single‐stranded DNA, play critical roles in gene expression and genome stability. How R‐loop homeostasis is integrated into chloroplast gene expression remains largely unknown. We found an unexpected function of FtsHi1, an inner envelope membrane‐bound AAA‐ATPase in chloroplast R‐loop homeostasis of Arabidopsis thaliana . Previously, this protein was shown to function as a component of the import motor complex for nuclear‐encoded chloroplast proteins. However, this study provides evidence that FtsHi1 is an ATP‐dependent helicase that efficiently unwinds both DNA–DNA and DNA–RNA duplexes, thereby preventing R‐loop accumulation. Over‐accumulation of R‐loops could impair chloroplast transcription but not necessarily genome integrity. The dual function of FtsHi1 in both protein import and chloroplast gene expression may be important to coordinate the biogenesis of nuclear‐ and chloroplast‐encoded subunits of multi‐protein photosynthetic complexes. This study suggests a mechanical link between protein import and R‐loop homeostasis in chloroplasts of higher plants.
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