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EMBO J. 2018 Jan 17;37(2):255-268. doi: 10.15252/embj.201797159. Epub 2017 Dec 12.

The Arabidopsis ALF4 protein is a regulator of SCF E3 ligases.

Author information

1
Howard Hughes Medical Institute, University of California San Diego, La Jolla, CA, USA.
2
Sainsbury Laboratory, University of Cambridge, Cambridge, UK.
3
Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, Halle, Germany.
4
Institute of Biology, Structural Biology/Biochemistry, Humboldt-University Berlin, Berlin, Germany.
5
Plant Systems Biology, Technische Universität München, Freising, Germany.
6
Howard Hughes Medical Institute, University of California San Diego, La Jolla, CA, USA mestelle@ucsd.edu.

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

PMID:
29233834
PMCID:
PMC5770881
[Available on 2019-01-17]
DOI:
10.15252/embj.201797159

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