J Integr Plant Biol. ›› 2021, Vol. 63 ›› Issue (4): 772-786.DOI: 10.1111/jipb.13045

Special Issue: Epigenetics

• Molecular Physiology • Previous Articles     Next Articles

A novel protein complex that regulates active DNA demethylation in Arabidopsis

Pan Liu1,2†, Wen‐Feng Nie1,3†*, Xiansong Xiong1,2, Yuhua Wang1, Yuwei Jiang1,2, Pei Huang1,2, Xueqiang Lin1, Guochen Qin1, Huan Huang1, Qingfeng Niu1, Jiamu Du1, Zhaobo Lang1, Rosa Lozano‐Duran1 and Jian‐Kang Zhu1,4*   

  1. 1Shanghai Center for Plant Stress Biology, Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China
    2University of Chinese Academy of Sciences, Beijing 100049, China
    3Department of Horticulture, College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China
    4Department of Horticulture & Landscape Architecture, Purdue University, West LafayetteIndiana 47906, USA

    These authors contributed equally.
    *Correspondences: Wen‐Feng Nie (wfnie@yzu.edu.cn); Jian‐Kang Zhu (jkzhu@psc.ac.cn, Dr. Zhu is responsible for the distribution of the materials associated with this article)
  • Received:2020-11-21 Accepted:2020-12-01 Online:2020-12-04 Published:2021-04-01

Abstract: Active DNA demethylation is critical for altering DNA methylation patterns and regulating gene expression. The 5‐methylcytosine DNA glycosylase/lyase ROS1 initiates a base‐excision repair pathway for active DNA demethylation and is required for the prevention of DNA hypermethylation at 1 000s of genomic regions in Arabidopsis. How ROS1 is regulated and targeted to specific genomic regions is not well understood. Here, we report the discovery of an Arabidopsis protein complex that contains ROS1, regulates ROS1 gene expression, and likely targets the ROS1 protein to specific genomic regions. ROS1 physically interacts with a WD40 domain protein (RWD40), which in turn interacts with a methyl‐DNA binding protein (RMB1) as well as with a zinc finger and homeobox domain protein (RHD1). RMB1 binds to DNA that is methylated in any sequence context, and this binding is necessary for its function in vivo. Loss‐of‐function mutations in RWD40, RMB1, or RHD1 cause DNA hypermethylation at several tested genomic regions independently of the known ROS1 regulator IDM1. Because the hypermethylated genomic regions include the DNA methylation monitoring sequence in the ROS1 promoter, plants mutated in RWD40, RMB1, or RHD1 show increased ROS1 expression. Importantly, ROS1 binding to the ROS1 promoter requires RWD40, RMB1, and RHD1, suggesting that this complex dictates ROS1 targeting to this locus. Our results demonstrate that ROS1 forms a protein complex with RWD40, RMB1, and RHD1, and that this novel complex regulates active DNA demethylation at several endogenous loci in Arabidopsis.

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