J Integr Plant Biol. ›› 2021, Vol. 63 ›› Issue (4): 755-771.DOI: 10.1111/jipb.13052

Special Issue: Biotechnology Epigenetics Flowering

• Molecular Physiology • Previous Articles     Next Articles

The CBP/p300 histone acetyltransferases function as plant‐specific MEDIATOR subunits in Arabidopsis

Jing Guo1,2, Long Wei1, Shan‐Shan Chen1, Xue‐Wei Cai1, Yin‐Na Su1, Lin Li1, She Chen1,3 and Xin‐Jian He1,2,3*   

  1. 1National Institute of Biological Sciences, Beijing 102206, China
    2Graduate School of Peking Union Medical College, Beijing 100730, China
    3Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100084, China

    *Correspondence: Xin-Jian He (hexinjian@nibs.ac.cn)
  • Received:2020-12-08 Accepted:2020-12-10 Online:2020-12-15 Published:2021-04-01

Abstract: In eukaryotes, MEDIATOR is a conserved multi‐subunit complex that links transcription factors and RNA polymerase II and that thereby facilitates transcriptional initiation. Although the composition of MEDIATOR has been well studied in yeast and mammals, relatively little is known about the composition of MEDIATOR in plants. By affinity purification followed by mass spectrometry, we identified 28 conserved MEDIATOR subunits in Arabidopsis thaliana, including putative MEDIATOR subunits that were not previously validated. Our results indicated that MED34, MED35, MED36, and MED37 are not Arabidopsis MEDIATOR subunits, as previously proposed. Our results also revealed that two homologous CBP/p300 histone acetyltransferases, HAC1 and HAC5 (HAC1/5) are in fact plant‐specific MEDIATOR subunits. The MEDIATOR subunits MED8 and MED25 (MED8/25) are partially responsible for the association of MEDIATOR with HAC1/5, MED8/25 and HAC1/5 co‐regulate gene expression and thereby affect flowering time and floral development. Our in vitro observations indicated that MED8 and HAC1 form liquid‐like droplets by phase separation, and our in vivo observations indicated that these droplets co‐localize in the nuclear bodies at a subset of nuclei. The formation of liquid‐like droplets is required for MED8 to interact with RNA polymerase II. In summary, we have identified all of the components of Arabidopsis MEDIATOR and revealed the mechanism underlying the link of histone acetylation and transcriptional regulation.

Editorial Office, Journal of Integrative Plant Biology, Institute of Botany, CAS
No. 20 Nanxincun, Xiangshan, Beijing 100093, China
Tel: +86 10 6283 6133 Fax: +86 10 8259 2636 E-mail: jipb@ibcas.ac.cn
Copyright © 2022 by the Institute of Botany, the Chinese Academy of Sciences
Online ISSN: 1744-7909 Print ISSN: 1672-9072 CN: 11-5067/Q