J Integr Plant Biol. ›› 2021, Vol. 63 ›› Issue (8): 1451-1461.DOI: 10.1111/jipb.13155

• Cell and Developmental Biology • Previous Articles     Next Articles

Genetic analysis implicates a molecular chaperone complex in regulating epigenetic silencing of methylated genomic regions

Zhengyan Feng1†, Xiangqiang Zhan2†, Jia Pang1,3, Xue Liu1, Huiming Zhang1, Zhaobo Lang1 and Jian‐ Kang Zhu1*   

  1. 1 Shanghai Center for Plant Stress Biology and Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China
    2 State Key Laboratory of Crop Stress Biology for Arid Areas and College of Horticulture, Northwest A&F University, Yangling 712100, China
    3 University of Chinese Academy of Sciences, Beijing 100049, China

    These authors contributed equally to this work.
    *Correspondence: Jian‐Kang Zhu (jkzhu@psc.ac.cn)
  • Received:2021-07-11 Accepted:2021-07-19 Online:2021-07-21 Published:2021-08-01

Abstract: DNA cytosine methylation confers stable epigenetic silencing in plants and many animals. However, the mechanisms underlying DNA methylation-mediated genomic silencing are not fully understood. We conducted a forward genetic screen for cellular factors required for the silencing of a heavily methylated p35S:NPTII transgene in the Arabidopsis thaliana rdm1-1 mutant background, which led to the identification of a Hsp20 family protein, RDS1 (rdm1-1 suppressor 1). Loss-of-function mutations in RDS1 released the silencing of the p35S::NPTII transgene in rdm1-1 mutant plants, without changing the DNA methylation state of the transgene. Protein interaction analyses suggest that RDS1 exists in a protein complex consisting of the methyl-DNA binding domain proteins MBD5 and MBD6, two other Hsp20 family proteins, RDS2 and IDM3, a Hsp40/DNAJ family protein, and a Hsp70 family protein. Like rds1 mutations, mutations in RDS2, MBD5, or MBD6 release the silencing of the transgene in the rdm1 mutant background. Our results suggest that Hsp20, Hsp40, and Hsp70 proteins may form a complex that is recruited to some genomic regions with DNA methylation by methyl-DNA binding proteins to regulate the state of silencing of these regions.

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