The Arabidopsis ALF4 protein is a regulator of SCF E3 ligases

Abstract

The cullin-RING E3 ligases (CRLs) regulate diverse cellular processes in all eukaryotes. CRL activity is controlled by several proteins or protein complexes, including NEDD8, CAND1, and the CSN. Recently, a mammalian protein called Glomulin (GLMN) was shown to inhibit CRLs by binding to the RING BOX (RBX1) subunit and preventing binding to the ubiquitin-conjugating enzyme. Here, we show that Arabidopsis ABERRANT LATERAL ROOT FORMATION4 (ALF4) is an ortholog of GLMN. The alf4 mutant exhibits a phenotype that suggests defects in plant hormone response. We show that ALF4 binds to RBX1 and inhibits the activity of SCFTIR1, an E3 ligase responsible for degradation of the Aux/IAA transcriptional repressors. In vivo, the alf4 mutation destabilizes the CUL1 subunit of the SCF. Reduced CUL1 levels are associated with increased levels of the Aux/IAA proteins as well as the DELLA repressors, substrate of SCFSLY1. We propose that the alf4 phenotype is partly due to increased levels of the Aux/IAA and DELLA proteins.

Keywords

auxin; cullin-RING E3 ligases; glomulin; plant development

Published in

EMBO Journal
2018, Volume: 37, number: 2, pages: 255-268 Publisher: WILEY

SLU Authors

• Melnyk, Charles

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    
  • University of Cambridge

UKÄ Subject classification

Biochemistry and Molecular Biology


Publication identifier

DOI: https://doi.org/10.15252/embj.201797159

Permanent link to this page (URI)

https://res.slu.se/id/publ/93829