Identification of Arabidopsis MYB56 as a novel substrate for CRL3BPM E3 ligases

Liyuan Chen; Anne Bernhardt; JooHyun Lee; Hanjo Hellmann

doi:10.1093/mp/ssu120

Identification of Arabidopsis MYB56 as a novel substrate for CRL3BPM E3 ligases

Mol Plant. 2014 Oct 24:ssu120. doi: 10.1093/mp/ssu120. Online ahead of print.

Authors

Liyuan Chen¹, Anne Bernhardt², JooHyun Lee³, Hanjo Hellmann⁴

Affiliations

¹ Washington State University, Pullman, WA, 99163, USA current address: Plant Gene Expression Center, UC Berkeley, Albany, CA 94710, USA.
² Washington State University, Pullman, WA, 99163, USA current address: Robert Koch Institut, 13353 Berlin, Germany.
³ Washington State University, Pullman, WA, 99163, USA.
⁴ Washington State University, Pullman, WA, 99163, USA hellmann@wsu.edu.

PMID: 25343985
DOI: 10.1093/mp/ssu120

Abstract

Controlled stability of proteins is a highly efficient mechanism to direct diverse processes in living cells. A key regulatory system for protein stability is given by the ubiquitin proteasome pathway, which uses E3 ligases to mark specific proteins for degradation. In this work MYB56 is identified as a novel target of a CULLIN3 (CUL3)-based E3 ligase. Its stability depends on the presence of MATH-BTB/POZ (BPM) proteins, which function as substrate adaptors to the E3 ligase. Genetic studies pointed out that MYB56 is a negative regulator of flowering, while BPMs positively affect this developmental program. The interaction between BPMs and MYB56 occurs at the promoter of FLOWERING LOCUS T (FT), a key regulator in initiating flowering in Arabidopsis, and results in instability of MYB56. Overall the work establishes MYB transcription factors as substrates of BPM proteins, and provides novel information on components that participate in controlling the flowering time point in plants.

Keywords: BPM; CUL3; E3 ligase; MYB; flowering; transcription factor.