Abstract
Calmodulin (CaM), a key Ca(2+) sensor in eukaryotes, regulates diverse cellular processes by interacting with many proteins. To identify Ca(2+)/CaM-mediated signaling components, we screened an Arabidopsis expression library with horseradish peroxidase-conjugated Arabidopsis calmodulin2 (AtCaM2) and isolated a homolog of the UBP6 deubiquitinating enzyme family (AtUBP6) containing a Ca(2+)-dependent CaM-binding domain (CaMBD). The CaM-binding activity of the AtUBP6 CaMBD was confirmed by CaM mobility shift assay, phosphodiesterase competition assay and site-directed mutagenesis. Furthermore, expression of AtUBP6 restored canavanine resistance to the Deltaubp6 yeast mutant. This is the first demonstration that Ca(2+) signaling via CaM is involved in ubiquitin-mediated protein degradation and/or stabilization in plants.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Motifs
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Amino Acid Sequence
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Arabidopsis / enzymology*
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Arabidopsis Proteins / physiology*
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Binding, Competitive
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Calcium / metabolism
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Calmodulin / metabolism*
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Canavanine / chemistry
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Canavanine / pharmacology
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Dose-Response Relationship, Drug
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Endopeptidases / metabolism
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Endopeptidases / physiology*
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Gene Library
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Genetic Complementation Test
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Glutathione Transferase / metabolism
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Horseradish Peroxidase / metabolism
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Humans
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Models, Genetic
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Mutation
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Peptides / chemistry
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Phosphoric Diester Hydrolases / metabolism
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Protein Binding
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Protein Structure, Tertiary
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Sequence Homology, Amino Acid
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Signal Transduction
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Ubiquitin / chemistry
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Ubiquitin / metabolism
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Ubiquitin-Specific Proteases
Substances
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Arabidopsis Proteins
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CALM2 protein, human
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Calmodulin
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Peptides
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Ubiquitin
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Canavanine
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Horseradish Peroxidase
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Glutathione Transferase
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Phosphoric Diester Hydrolases
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Endopeptidases
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Ubiquitin-Specific Proteases
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Calcium