Role of the Arabidopsis RING-H2 protein RBX1 in RUB modification and SCF function

William M Gray; Hanjo Hellmann; Sunethra Dharmasiri; Mark Estelle

doi:10.1105/tpc.003178

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Role of the Arabidopsis RING-H2 protein RBX1 in RUB modification and SCF function

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Role of the Arabidopsis RING-H2 protein RBX1 in RUB modification and SCF function

William M Gray, Hanjo Hellmann, Sunethra Dharmasiri and Mark Estelle

The Plant cell, Vol.14(9), pp.2137-2144

09/2002

DOI: https://doi.org/10.1105/tpc.003178

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https://hdl.handle.net/2376/106145

PMCID: PMC150761

PMID: 12215511

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Abstract

Amino Acid Sequence

Arabidopsis Proteins - genetics

Arabidopsis Proteins - physiology

Peptide Synthases - physiology

Arabidopsis - growth & development

Ligases - genetics

Gene Expression Regulation, Developmental - drug effects

Ligases - metabolism

Molecular Sequence Data

Peptide Synthases - genetics

Arabidopsis - metabolism

Arabidopsis - genetics

Arabidopsis Proteins - metabolism

SKP Cullin F-Box Protein Ligases

Sequence Homology, Amino Acid

Ubiquitin-Protein Ligases

Gene Expression Regulation, Plant - drug effects

Indoleacetic Acids - pharmacology

Plants, Genetically Modified

Ligases - physiology

Mutation

Ubiquitin-Conjugating Enzymes

Ubiquitins - metabolism

The ubiquitin-related protein RUB/Nedd8 is conjugated to members of the cullin family of proteins in plants, animals, and fungi. In Arabidopsis, the RUB conjugation pathway consists of a heterodimeric E1 (AXR1-ECR1) and a RUB-E2 called RCE1. The cullin CUL1 is a subunit in SCF-type ubiquitin protein ligases (E3s), including the SCF(TIR1) complex, which is required for response to the plant hormone auxin. Our previous studies showed that conjugation of RUB to CUL1 is required for normal SCF(TIR1) function. The RING-H2 finger protein RBX1 is a subunit of SCF complexes in fungi and animals. The function of RBX1 is to bind the ubiquitin-conjugating enzyme E2 and bring it into close proximity with the E3 substrate. We have identified two Arabidopsis genes encoding RING-H2 proteins related to human RBX1. Studies of one of these proteins indicate that, as in animals and fungi, Arabidopsis RBX1 is an SCF subunit. Reduced RBX1 levels result in severe defects in growth and development. Overexpression of RBX1 increases RUB modification of CUL1. This effect is associated with reduced auxin response and severe growth defects similar to those observed in axr1 mutants. As in the axr1 mutants, RBX1 overexpression stabilizes the SCF(TIR1) substrate AXR2/IAA7. The RBX1 protein is a component of SCF complexes in Arabidopsis. In addition to its direct role in SCF E3 ligase activity, RBX1 promotes the RUB modification of CUL1 and probably functions as an E3 ligase in the RUB pathway. Hypermodification of CUL1 disrupts SCF(TIR1) function, suggesting that cycles of RUB conjugation and removal are important for SCF activity.

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Title: Role of the Arabidopsis RING-H2 protein RBX1 in RUB modification and SCF function
Creators: William M Gray - Molecular, Cell, and Developmental Biology Section, The University of Texas, Austin, Texas 78712, USA
Hanjo Hellmann
Sunethra Dharmasiri
Mark Estelle
Publication Details: The Plant cell, Vol.14(9), pp.2137-2144
Academic Unit: Biological Sciences, School of
Publisher: United States
Grant note: R01-GM43644 / NIGMS NIH HHS R01 GM043644 / NIGMS NIH HHS
Identifiers: 99900547119201842
Language: English
Resource Type: Journal article