Characterization of the Ubiquitin E2 Enzyme Variant Gene Family in Arabidopsis

Authors

  • Yu Zhang,

    1. National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing 102206, China
    2. Peking-Yale Joint Center for Plant Molecular Genetics and Agro-biotechnology, College of Life Sciences, Peking University, Beijing 100871, China
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    • *

      These authors contributed equally to this work.

  • Pei Wen,

    1. National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing 102206, China
    2. College of Life Sciences, Beijing Normal University, Beijing 100875, China
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    • *

      These authors contributed equally to this work.

  • On-Sun Lau,

    1. Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104, USA
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  • Xing-Wang Deng

    Corresponding author
    1. National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing 102206, China
    2. Peking-Yale Joint Center for Plant Molecular Genetics and Agro-biotechnology, College of Life Sciences, Peking University, Beijing 100871, China
    3. Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104, USA
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  • Publication of this paper is supported by the National Natural Science Foundation of China (30624808) and Science Publication Foundation of the Chinese Academy of Sciences.

**Author for correspondence. Tel: +1 203 432 8908; Fax: +1 203 432 5726; E-mail: <xingwang.deng@yale.edu>.

Abstract

Ubiquitin E2 enzyme variant (UEV) proteins are similar to ubiquitin-conjugating enzyme (E2) in both sequence and structure, but the lack of a catalytic cysteine residue renders them incapable of forming a thiol-ester linkage with ubiquitin. While the functional roles of several UEVs have been defined in yeast and animal systems, Arabidopsis COP10, a photomorphogenesis repressor, is the only UEV characterized in plants. Phylogenetic analysis revealed that the eight Arabidopsis UEV genes belong to three subfamilies. The expression of those genes is supported by either the presence of ESTs or RT-PCR analysis. We also characterized the other members of the COP10 subfamily, UEV2. Semi-quantitative RT-PCR analysis indicated that the UEV2 transcripts can be detected in most organs of Arabidopsis. Analysis of UEV2::GUS transgenic lines also showed its ubiquitous expression in nearly all the developmental stages of Arabidopsis. Transient expression analysis indicated that the sGFP-UEV2 fusion protein can localize to both the cytoplasm and nucleus. A T-DNA insertion mutant, uev2-1, which abolished the transcription of UEV2, displays no visible phenotype. Further, the cop10-4 uev2-1 double mutant exhibits the same phenotype as the cop10-4 mutant in darkness. UEV2 is therefore not functionally redundant with COP10.

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